But just as a counter example, our boat is set up assuming an inverter running 24x7. Refrigeration, ventilation (bathrooms and machinery space), fresh water pump, ER lighting are all 120V AC. The boat could have been set up differently, but considering how reliable inverter (good ones) are, it makes a lot of sense to just use AC for these appliances. In fact, our entire 120V service is inverter based. Switching from inverter to shore power or generator is automatic and seamless. Computers don't restart, TVs don't blink. It's transparent to all the loads. And charging then kicks in after a short delay. I wouldn't do it any other way, even on a smaller boat. And the setup ends up being more reliable, not less reliable. We have lost shore power a number of time for up to a day, and our boat just keeps ticking on. Obviously you need to not run for too long and run down the batteries, but 99% of the power interruptions become transparent. I remember a number of years ago when there was a total failure of the NE power grid lasting for a couple of days. I didn't even know about it until into the 2nd or 3rd day I happened to turn on the radio to catch the news. The same has happened with multiple ice storms that have taken out local power for days at t time.
But I agree there are lots of ways to set up a system poorly, with poor results. And plenty of crappy equipment out there. But when done well, the results are excellent.