the fact that you're even suggesting it is making me overthink it. why not? i'll tell you why not:
-because it's a big enough significant event for the MCU to crossover with the Raimi and ASM universes. If they are bringing in Tobey's Spider & Andrew's Spider to have them be alternate versions of the characters we saw in the movies, nothing then really is being added to their legacies since they're technically not the same characters. But the whole appeal of all this is to add to their legacies
-because it would make more sense for the supposed alternate Tobey Spider & Andrew Spider to feel responsible for their missing villains in alternate universe, they would feel the actual concern. In fact, if the original Tobey & Andrew return to fight alternate versions of their villains, then the alternate Tobey & Andrew would never get their due closure.
-because just writing it off as "it's multiverse of madness" really just comes off as nothing more than a copout answer