> those legal protections are useless for the majority of purchases

I think you're misunderstanding the protections we're talking about.

When someone steals my credit card and spends $10k on it, I just dispute it. The charges don't show up on my bill until after the investigation happens, and chances are it will be found in my favor. I continue having my cash in my bank account. Life continues with no changes.

When someone steals my debit card and spends all my cash, I dispute it. They begin their investigation. This means I'm without all my cash for days, maybe weeks, while they do their investigation. Now I can't pay rent. Now I can't buy groceries. My life is pretty messed up at this point.

I've seen it happen to several people personally. It happens all the time.