> 100K DAU

> but you also don't want a PHP/MySQL monolith if you're building something that works like, say, Twitter

This is a lot of whiplash in regards to discussing size.

I just want to say...

100K DAU with a PHP/MySQL monolith is 100% possible - I'm certain a lot of people here have achieved this without much problem. Things like Nginx, PHP-FPM, reverse-proxy-caching, load balancing to stateless application servers, read replica, offloading static assets to CDN, blah blah... I digress but you can 100% hit 100K DAU with a traditional PHP/MySQL monolith.