Because running in the oppression olympics is the easiest way to gain status in most western societies.

I would argue that the sentimental compassion it exploits is a very specifically American feature and it is less efficient elsewhere. If I had to guess, American culture has uniquely selfish subsets (such as the Ayn Rand fans), and as a reaction, the opposite shine-with-goodness attitude evolved which then gets exploited. What you see is the middle ground missing, probably.

A good example is middle-class people seeing the welfare state either sentimentally as hearts going out for the poor, or the judgemental "bunch of lazy leeches" view which are both moralistic. What middle ground is missing is the simple "customer" attitude to the welfare state "well, I might need it any time, better make sure it works right, potentially for ME" which is the most common European attitude. This middle ground is missing, because there is a tribe that derives identity from shining-with-goodness, and another tribe from selfishness, usually interpreting selfishness as toughness.

Both can be exploited. Oppression olympics exploits the shine-with-goodness tribe and shit like not even a year of paid maternity leave exploits the my-selfishness-is-toughness tribe.

But I think in Western societies who go for the middle in things like this, oppression olympics e.g. complaining about misgendering generally gets answers roughly like "But I am just doing what the rules and social customs permit / prescribe?" with the connotation "Why exactly would I care about your personal feelings?"