Serrated knives are for sawing, not slicing. They don't really need to be particularly sharp. Chopping knives are similar; a dull chopping knife will waste your time, but isn't particularly dangerous. But a dull paring knife, or a dull wood carving chisel? Beware.

Anyway, per the rest of this discussion, definition of 'gatekeeping' is clearly contextual. Paraphrasing the exchange above: "What about safety?", "Sure, but that's not what we usually mean by gatekeeping."

Telling somebody they shouldn't weld without goggles isn't gatekeeping, it's safety advice. Telling somebody they aren't a real welder because they're using a cheap but functional brand of welder is gatekeeping, because there's no good reason to malign a welder for having an unfashionable brand of equipment.

Gatekeeping is only 'true' gatekeeping if there isn't a good reason for keeping that gate; safety advice in particular is generally exempted. Since gatekeeping is only true gatekeeping in contexts where there isn't a good reason for it, claiming that something is gatekeeping without explaining why is basically worthless. Such accusations are assertions without supporting arguments. It often boils down to circular reasoning: You're gatekeeping which is bad, and it's bad because it's gatekeeping.