Why pay 1% or whatever fees to buy BTC with fiat and then pay with it at an unknown premium, if you can pay with fiat directly and get cashback?

But don't worry. More merchants will start accepting BTC in the next bull run, because many people will want to dispose of their sats without going through exchanges, and if there are tax advantages to that (e.g. tax free <$200 purchases), they'll have even more reasons.