Because math lets you make the same assumptions with a much smaller data set. Even if they did send out a survey to everyone, people would then complain that “well the results are skewed because some players have multiple accounts, and because multiple account holders love spending money, then they must love microtransactions, so obviously they are retail players, so of course they want cata. The survey’s aren’t fair”
If they recently banned 200k accounts, that’s 200k surveys that could be answered by people who ruin the game for their financial advantage, so they are going to vote in a way to make more money. And if a bot runner can answer surveys to their benefit, 100% of the bots are replying to the survey, where as real players will probably ignore the survey entirely, skewing it even more.
(200k account closure source: Recent Actions Against Exploitative Accounts – October 2023)