I mean the actual medicine part. When I think about it, there are still no cures for the major things that ail us (e.g. cancer, etc.). China cured that one guy from his diabetes, but I haven't heard anything beyond that.
The "promise" of stem cell technology from 20 years ago still hasn't amounted to anything that your average person can get (and there are all sorts of shady overseas places that give ppl "stem cell" injections, but honestly we should have figured out that shit by now).
If you tear a ligament/tendon, guess what, that shit will never heal back to 100%, and the "oh just rest and do physical therapy" shit is annoying because you're only really working around the problem and not solving it.
On top of that, as you get older it's harder for your body to heal from injuries, sickness, etc. and I've yet to see any legit progress on anti-aging. If your heart is damaged or arteries clogged, I don't see any way to reverse it.
And after covid, it's all been fucked. How many people have long covid and the medical establishment just throws it's hands up 
basically treating an entire segment of the population as though it was a bad crop yield ("I guess there's always the next batch!!).
And doctors themselves are often the biggest dipshits out there. They are high off their own supply because they're "smart" and lack the empathy to actually listen to patients. Either they're older conservative types or younger lib dipshits. And there are so many horror stories about nurses that talk shit about patients. It's just dismal.
The common reply is that "biology is hard" but honestly that's a WEAK excuse. So many advances were made in the past, and there are so many more to be made. An actual concerted international effort, unhindered by profit motives and fucking insurance, hospital, pharmaceutical industries, etc. would almost certainly yield results. I mean look at Cuba coming up with a lung cancer vaccine and curing HIV in an infant. Look at China curing diabetes in that one guy. These advances are possible, but honestly they aren't coming fast enough. If you're suffering from a terrible disease/ailment, the "promise" of a new drug that still may be 10 years away is just terrible.
So even if we had 100% socialism now with free healthcare, there are still so many things that need to be addressed. I can't help but think that had the Soviet Union not fallen, we would have had cures for many things. Hopefully 
can do something about this, but overall I'm still super bummed that the future we dreamed has not materialized.
I mean I know you don't want to hear this, but it is hard and incredibly complex. "Curing cancer" would be basically the same as curing thousands of diseases simultaneously, you'd need a different cure for each type of cancer and how it effects different cells. Biomechanics are complicated with ligaments, tendons, bones and soft tissue. For instance, the best surgery we have at the moment for severe scoliosis or kyphosis (someone's spine growing skew in various different ways) still boils down to taking most of the affected vertebrae (often around a dozen vertebrae), and fusing them all together into one big bone/vertebrae that's straightened out, with what amounts to permanent braces that never get removed (metal screws and rods) that hold the vertebrae in place while they form into one big bone. Yes, that's how it's "fixed", by losing most of the mobility in your spine.
Yeah but this is what people say to dismiss socialism/communism. "It's too complex, human nature, etc. etc."
Sure but the one thing that unites all cancer cells is uncontrolled cell division. And your body's immune system is constantly killing rogue cancer cells here and there, but sometimes they slip through (usually due to age-related immune decline). So I could see a therapy that attacks it from that angle. So I really don't buy the whole "cancer is ackshually a bajillion different types of diseases!" thing honestly.
I see stem cells playing a huge role in these kinds of things. I've been seeing legit research on the use of mesenchymal stem cells in pretty much healing these kinds of things.
Basically all the concerns you're talking about could have been said about a whole slew of things that seemed "incurable" 100-200 years ago but are a piece of cake now.
Isn't that just almost magical thinking, to think we can prevent uncontrolled cell division or immune system decline from age, from ever happening in the first place with our current technology? That's why a lot of experts think the most realistic approach at this point in time to treat cancer is treating each type of cancer differently. If the alternative to "not buying that theory" is to try find a magic bullet cure to stop all uncontrolled cell division and aging, that's most likely going to take a lot longer to come to fruition than targeting different types of cancers on an individual basis.
Didn't you also say that "The "promise" of stem cell technology from 20 years ago still hasn't amounted to anything that your average person can get", and now you're suggesting that stem cell therapy can heal tendon, ligament, bone, and soft tissue injuries. That's a really wide range of injuries. I surely hope that is true, but logically I can't see how that could be.
If I'm reading OP charitably, I think they mean that in our current system, it hasn't amount to anything due to profit motives, etc. but that it isn't inherently wrong to think that stem cells can work.
Your takes on healthcare are equivalent of people mad that Xi hasn't pushed the communism button