PHP is inherently stateless, making it easy to scale up. Facebook has had pretty close to a 100% availability rate since launch and PHP is still responsible for large swathes of their functionality.
Most people attacking PHP read a snarky article written in 2012 about PHP's limitations and cannot actually provide reasoning for why it's so awful.
Wikipedia, huge portions of online retail, forums and Facebook. Are these things inherently less secure or available than companies with a "modern" stack? Not really, in fact pretty much the opposite.
I'll let you in on a little secret: your customers could not care less about your shiny modern stack. As long as it's not preventing performance, security and new development then they don't care.
My PHP endpoints respond in <100ms, which to my customers is perceptionally instantaneous. They wouldn't benefit from any shiny modern language at all (but I do use them).
Thats what every Rust-Fanboy says about the C/C++ Ecosystem
I'm just calling it for what it is: a broken tool. I'm suggesting we let go of this broken tool and focus on tools that already work great, instead of wasting millions of human work hours on sub-par coding. Sure, you can still make billions with broken tools, but you could also have done that more easily with the right tools.