Flash still exists if you want it, it is just called Haxe now. Both major and a number of minor game development platforms can publish to the web. Checking itch.io there were 120 web based games uploaded within the past day (includes updates I assume). I would guess there are more now than ever before, but because there are more easily available commercial games for very little money on sale more people just get commercial games. Or download free games, which gives better controls than a browser. Although the games market in general is so much larger now that I'm not conviced there are fewer people interested in web games than previously. I suspect it is more a case of people who were personally interested in web games previously and aren't now thinking that it is no longer a thing.