Bitcoin price goes up and down all the time. If someone buys something costing 10$, the next day it may cost less or more. So it's a risk for the seller.
If they are going to be converting it to fiat at the end of the day, then it’s of no need. It would be better for them to just accept fiat and nothing else. And moreover, there is a fee that is being charged when you try converting your coins to fiat or another cryptocurrency.
Cryptocurrency is good, but I won’t recommend it to a small business. A small business that is making use of cryptocurrency might be experiencing loss, because of the processes that will be involved in converting and withdrawing their money. Big businesses are the ones that can accept Bitcoin, because they will still cover up the fees and wouldn’t mind if the price of Bitcoin drops.