I don't think there's any reason to get angered by any of this. There are a lot of misconceptions about the different types of guns and their use in home defense. Not everyone wants to be educated, or wants to believe that person they trust could be wrong. When they want to, they'll get training, or ask for proper advise, and then get training.
The short and skinny though is... any gun is good for home defense. As long as you know how to use it properly, in any given scenario, in and around your home. Know your chosen firearms's strengths and weaknesses, and how to workaround them safety and effectively.
Specifically to shotguns though.... Pump's require extra training and practice for use under stress, and have much more recoil than a semi-auto. Shotguns are loud, and will probably stun the crap out of you the first time you fire one indoors without ear protection. Long guns are very cumbersome to manipulate indoors, even the 16" and 18" variety.
But they can be used effectively, and may even be the best choice for you. Cost is an issue, but if you insist on a shotgun I would only recommend the semi-auto variety. They are very reliable today, require less manipulation, and have much less recoil. That said I have a 18" Mossberg 88 as my 2nd go to in the house, hehe.