Who have people been using that excuse for? It doesn't make sense to me; the fact that we have Ridley (canonically dead since Super Metroid), Simon Belmont (who would be long-since dead during Richter's games), Marth (not sure how the Fire Emblem games are connected, but he's a distant ancestor of Chrom and Lucina), Mega Man (maybe? by the time of Mega Man X), and various Links and Zeldas by whatever the latest game in the Zelda timeline is seems to indicate otherwise.
(EDIT: Forgot Dark Samus.)
There's one other example that I had, but I wasn't sure if it was spoilery. I assume they're talking about a particular Tekken character, though I'm not 100% sure without context.