If you wanted to create something that's better than the pages we had in the Geocities era, you can do that in 5 minutes (download some static page generator, add a theme and voila).
When it was unveiled, the GMail frontend was a remarkable feat of engineering. Nowadays? Polishing to that extent (also scaling, etc) will take time, but creating a knockoff UI is no longer a revolutionary job. Most web developers would be able to single-handedly replicate the basic functionality ('ajax' and lots of client side javascript are no longer arcane).
As web development progressed, so did expectations.
I wrote a web app the other day with vanilla Python, it doesn't do much (it's a tasks app for my wife and I), but it does it's job, and in one file even! It doesn't use fancy front end stuff, just HTML template strings and some links that send CRUD ops to the server, then that saves the data in a big text file. It uses CSS to make it look nice.
I bet I could get a hundred people using it without edits, and it took a few hours. With a proper database and server, it would support thousands easily.