Yes, but the users aren't going to ask for refunds. Also they feel that because it's free they aren't really entitled to customer service (and you certainly wouldn't offer them any).
Your original seems to suggest that loss of revenue from software not working will be more severe for directly-paid software than for ad-supported software. It's not clear to me that's the case, especially given that some of the highest revenue software currently in use (consumer services from FB etc.) is ad-supported.
Anyway, this is tangential to this thread, so I won't go on about it.
Anyway, this is tangential to this thread, so I won't go on about it.