Yeah, they all had their shortcomings, which meant they had to be replaced instead of evolved, because in the Linux community it is extremely hard to evolve a project in a better direction, but creating a new project is easy, and even getting that project into distros can be easier than evolving older projects.
Unfortunately this means that rather than being natively backwards-compatible, you end up with a tower of cards of compatibility layers which tend in my experience to collapse…
Well, yes. This distinction is only meaningful now on really old hardware where upgrading RAM or replacing the machine is not an option (maybe it has some other critical bit of hardware or, more likely, it’s a hobby project and the owner just wants to keep using it as long as possible for fun and satisfaction)
The difference between the minimal RAM usage of a lightweight Linux installation and a Windows installation is the cost of less than £50 of modern RAM, never mind whatever old stuff is needed for an older machine.