> you were supposed to mix HTML and PHP in one file. Easy to do and easy to make bugs.
I maintain a large project (inherited) that has that; cannot say it's been that bad in my experience; it has been running for 20 years and used (internally and externally; it's a crm/erp/everything system) used by 1000s daily; no significant bugs have been reported and adding/changing features is fast and painless. I sometimes wonder if that over-architected stuff we have been taught really is much better. For most things here I change one (or 2) file, test, deploy, done. For most other stuff I maintain, for every change I have to change 5-10 files all over the place (service layers, data layers, migrations etc) and the result is not really better (I would say actually worse generally). It's not really apples vs apples (for starters, it is only used by this company and it's partners, while other systems are running publicly and have far more users and people trying to hack/break things) but this old system is causing me far less headaches than many others while it's far larger and more complex functionality wise.
Edit: many companies came in 'offering' a rewrite but yeah.. This costs nothing to host and barely anything to maintain (compared to the revenue of the company) ; all other solutions or rewrites would cost a lot to create/set up and then a lot to run/maintain as well. It's a good example of a company that would be insane to 'go cloud'. Not many benefits but a nice bite in the profit.