>I just don't understand this whole 'lock-in' mindset, it's just absurd now.

If you don't understand it, then it's probably not absurd.

Look into the whole free software movement and the history behind it (e.g. the evils of Microsoft in the 90s).

If a vendor can change a price on something that forces you to pay up or lose your system, you are locked in.

This isn't just some open source ideology without impacts either. It should be immediately obvious to anyone with any business acumen why making yourself beholden to the decisions of a single vendor is a bad position to be in.

The vital difference being that Docker and PHP aren't subscription-based, and aren't controlled by a single corporation.

Replace Docker and PHP with anything and the same is true tho.

If you write your application in any language, or use any framework or library, you're locked in, by today's standards.

The difference is that you can't be screwed by a single company deciding to change prices. When people refer to "lock-in", they are referring to being able to be screwed by a single vendor.

Nobody cares if they are locked into x86, tcp/ip, and http. If you don't understand this difference as an engineer, you end up causing a big risk to your company (or clients) without even knowing it.

Oh so now it’s paying for something that’s lock-in. This lock in sure keeps changing.