It's not by chance that in Europe even whilst becoming full-on Neoliberal parties, Center-Left parties maintained a leftwing discourse and would throw a bone to the Left once in a while (say, minimum wage raises) when in government.
Are you talking about nations with better electoral systems that can support more than 2 parties?
Yes, in a 3+ party system Party A moving closer to Party B to take 1000 votes from them but losing 1500 votes to Party C in the process is a bad play.
In a "Winner takes all" 2 party system where the only thing that matters is having 1 more vote than your opponent to have 100% of the power, Party A moving closer to Party B to take 1000 votes from them is a better position even if it causes them to lose 1900 votes from people who now won't vote for either party. Moving further away from Party B to get 1000 votes from people who are refusing to vote is a losing position if it causes them to lose 501 votes to Party B.
In a 2 party system chasing the people who are actually voting will always be twice as good than chasing the people who aren't voting.
So if Dick Cheney said "Russia is terrible, you should support Ukraine" you would oppose Ukraine because Dick Cheney supports them?
Opposing everything Dick Cheney does is mindless and is allowing Dick Cheney to decide what you support.
It looks like you're not going to vote for anyone anyway so why should either party care what you want?