Photopea is a full-featured web app, not website, written without frameworks by a single individual. It is absolutely possible to build feature rich applications without the framework du jour.
Team of 30 people is not needed to write fully featured application.
Team of 30 people is needed to build, run and maintain enterprise applications. Where you might need 24/7 support and such support requires at least 5 FTE, you might need features changed when 3 people go on 2 or 3 weeks vacations. Maybe that single person will come up with something better to do with their life so you need to have some people to take over.
What parent comment was about, people make broad statements not understanding that world is much bigger place.
Yea it is absolutely possible to build an app the way you describe but it doesn’t work for every app everywhere.
The same of course using React/Angular doesn’t work for everything, everywhere.
The only real viable alternative with a large team is a hand rolled framework, which isn't always worth the trade-off.