Ever heard of Erica the technology need who likes to film stuff?
She's very knowledgable. Watch one or 2 of her videos before making comments.
She bricked her SIII. Watch her S3 videos she mistakenly clicked on the wrong file because they were on top of each other. Ended up installing the one for a Note 2. She killed the phone.
Her fault for not double checking to make sure the files were correct. In many tutorials/install instructions I've seen there's always a "make sure you have the right file" disclaimer, especially if there are multiple ROMs on one page.
It's easy to flash a ROM and it's just as easy to brick it if one fails to follow instructions and doesn't double check files before flashing.
And as BK said, the dev community goes above and beyond with their work and careful instructions on how to install their ROM, making the process as simple as possible. They also have disclaimers saying they're not responsible if YOU brick YOUR phone. So yes it can happen to anyone, but it can easily be prevented by double checking the files to make sure they're the correct ones.
And as you said the regular user doesn't even know what a ROM is. They may have an idea and they may not be comfortable with the idea of it, but they still have the choice not to flash a ROM. I don't know about you, but every Android phone I've used has worked great out the box, many people who flash ROMs are just looking to further enhance their Android experience. If you frown upon that idea then that's your opinion, but don't say ROMs lead to nothing but trouble when you don't know the facts. If you don't feel Android phones are good enough out of the box, stick to whatever phone you're using since that's working out for you. Android is about choices; this phone or that phone, try X Y or Z ROM, or leave it stock? The choice is up to one person, the user.
I don't know what other boards you go to, but we here at DF fully support any adopter of Android and should they have any questions regarding their device we're here to help. Flashing a ROM, installing the latest app, changing up their homescreen, whatever it may be, we don't judge anyone's choice on their hardware and software because we like to keep an open mind, just as Google intended Android to be.