Also newer versions tend to be more taxing in the hardware, as it becomes more accurate and bigger in scope. Then the number of Roms exploded and it becomes harder to maintain newer versions. At some point, even non arcade games emulation was introduced and new rules to add arcade games as well. And each version requires a very specific set of roms and has sometimes drastically different commandline options in the official build of MAME. Sometimes there are bigger changes, which other programs would introduce a new mainline version. This fact makes it a bit difficult to follow as a regular user.
That means, with each new version breaking changes compared to previous versions are made to increase the quality of the preservation. Playing them well was just a nice side effect. MAME is a multi system emulator started to document arcade games as accurate as possible.
