Well, it 'should' have worked that way, but it's difficult to be certain that your explanation of events is in fact the actual reason - - as you say 'presumably' (but not definitely)
SFC is a flawed program, and (as noted in that linked thread) there are files that it restores 'incorrectly'
It might be interesting if you could list the files that were deemed to be corrupt
"My question is: Is SFC a good/needed program to install and run in WinME or not?"
To answer your *original* question: No, there's no verifiable reason to make use of that applet in WinME, your account notwithstanding. While your issue seemed to be resolved from this unorthodox method, that is far from a certainty. In order to perform its function, SFC compares files to an updatable 'baseline' database (default.sfc) - - it does not determine corruption merely by scanning the file. I have to wonder how useful the 'default.sfc' from Win98 would be within WinME - - if it was updated immediately, then the only corrupt files that might be found would have to have occurred after that initial scan - any 'corrupt' files in existence before that would be deemed 'ok' and recorded as the standard in the baseline
"Why didn't SFP protect, detect, and restore these files?"
That is another question entirely ; )
The short answer - - I don't know
It's difficult to perform a post mortem without knowing the exact circumstances. It can be appealing to believe a solution has been found, but things are not always as they seem, and coincidences can lead to leaps of logic
I'm not one of those who think Bill Gates is the devil. I simply suspect that if Microsoft ever met up with the devil, it wouldn't need an interpreter.