I actually agree with you about the monopoly point, but I'd still like to take a shot at answering some of those questions (with my opinions, of course).
1. If it increased the price it would then be pitted against the portable PCs, and they would be limiting their userbase. With console prices they know a lot more people will buy it just at the lower price point.
2. Two completely different markets. Mobile phones are taken everywhere, including jobs. People on their phones don't raise eyebrows at work, but people on a Switch definitely would.
3. More functionality is better. Usually you want to play portable, but sometimes you want to bring people over and play 4-player split screen. You don't want to do that on a tiny Switch screen.
4. The Switch can't really drop it's price much and still profit the way it does. And in fairness, the user did say "portable console". The Steam Deck is a portable PC. Most exclusive games aren't PC games, so there's still an argument for the Switch over the Steam Deck when it comes to exclusive content (unless we count piracy... which maybe could happen).
Still agree with you on the monopoly thing, but I thought it would be fun to respond to these points. I might be wrong on some or all of them. Those are just my opinions.