I finally got tired of seeing everyone call their pothos a philodendron at the local plant swap
It matters because they need different care, and I know from killing my first one in Portland by overwatering it thinking it was a heartleaf philodendron.
But is it really a big deal? They're both common houseplants that basically want the same thing. Bright indirect light, let them dry out a bit between waterings. People keep them alive for years without knowing the right name. Getting the name wrong at a swap seems pretty harmless.
Look at it from the collector's side though. They trade to find specific plants, not just any green thing. Mixing up names wastes their time and feels a bit lazy. It's about respecting the hobby and the other person's effort.