I definitely agree that running a B&B really is not for them - although does the husband never do any of the breakfast cooking/prep (or is he 'FoH')?
Maybe they're used to holiday makers who like a lie in before pootling off around the area late morning and afternoon - but even tourists will often like to get a good early-ish start, to make the most of their days.
If you'd said 7, I'd understand them maybe haggling for a bit later - although 7 is not unreasonably early - but 8 is normally in the middle of standard expected breakfast time when running a B&B/guest house, not before the beginning of it!
At the very least, they should prominently include 'Breakfast served from 8:30-10:00/9:00-10:30 (or whatever) in their advertising. That way, people who like to start their day later will be greatly attracted by being able to have a lie-in and still not miss breakfast, whilst people who like to get started at an earlier/more 'normal' time will know not to waste their or the hosts' time by booking there.
Back in the olden days, when you phoned up the tourist board to send you a brochure, we got a brochure of Blackpool accommodation sent to us (for our honeymoon, no less!) and we saw a place decked out in Rocky Horror colours that proudly proclaimed their 'party' atmosphere and the fact that you could get a cheeseburger at 3am. Just a hunch, but I'm guessing their guests probably weren't the earliest up for breakfast.
At the other end of the spectrum, there was a place where they were at great pains to stress that, if you were after a party-style atmosphere (iirc, I think they used the phrase 'knees up') and basically any kind of fun time whatsoever, it really wasn't the place for you. Maybe it was run by Sister Assumpta and designed as a retreat for those wishing to do penance, who knows.
Neither of these places were what we were looking for at all - and we found a lovely place almost exactly half-way in the middle of them - but I'm sure they each did fit the bill for plenty of compatible guests. Everybody knew where they stood and didn't end up booking somewhere unsuitable that would upset them or their hosts.