Many of these mistakes weren't even made by any committee, but were stuff shipped in a rush by Netscape or Microsoft to win the browser wars.
There was some (academic) reaserch behind early CSS concept, but the original vision for it didn't pan out ("cascading" was meant to blend style preferences of users, browsers and page authors, but all we got is selector specificity footguns).
Netscape was planning to release their own imperative styling language, and ended up shipping a buggy CSS hackjob instead.
Once IE was dominant, Microsoft didn't think they have to listen to anybody, so for a while W3C was writing CSS specs that nobody implemented. It's hard to do user research when nothing works and 90% of CSS devs' work is fighting browser bugs.
There was some (academic) reaserch behind early CSS concept, but the original vision for it didn't pan out ("cascading" was meant to blend style preferences of users, browsers and page authors, but all we got is selector specificity footguns).
Netscape was planning to release their own imperative styling language, and ended up shipping a buggy CSS hackjob instead.
Once IE was dominant, Microsoft didn't think they have to listen to anybody, so for a while W3C was writing CSS specs that nobody implemented. It's hard to do user research when nothing works and 90% of CSS devs' work is fighting browser bugs.