You’re right, hardware RAID still has some use for businesses, but it’s generally a bad idea for consumers. The main reason is the procedure if the RAID controller fails. In commercial applications they have spare, compatible controllers, so a quick hardware swap and you’re back up and running, you don’t even need to rebuild the array. However, consumers generally don’t have a spare controller, and if they don’t, they can’t just get any controller, they need a compatible one or the array is lost. If a system running a software RAID has a hardware failure, the array can be moved to a new host and mdadm can rebuild the array without needing specific hardware.