1. Millions of users, who play them happily each day.
2. Sites like Kongregate, Armor Games and Newgrounds, whose business is to publish them.
3. Sites like FlashGameLicense, whose business is to help the business of developing and publishing games that run in browsers.
If something can be done, someone will probably try to make a business out of it. If it catches on, then people who say "just because something is possible, doesn't mean it should be done" are wasting their breath.