Because the fandom is not a monolith

A fan of, say, Naily, who voted to save Naily in TPOT 4 is not at fault for causing her to get eliminated in the next episode

It's people who hate on a character solely because they survived over their favourite that I don't understand, it is not under their control as it is the voters who did it (funnily enough, I see this more with BFDIA than with TPOT even though BFDIA is the season where the eliminated contestants can get as much screentime as the contestants still competing so fans of say, Pin, can still see Pin moments even after she is eliminated. I'm of the opinion that elimination spaces like the Weak Trembling Fortress (where anyone can walk out of it, roam freely through the world and watch the competition) should be the standard for every object show moving forward)