What makes you think they're in a 2 gallon tank to start with?
And secondly, with one exception all my tanks are breeding tanks. And yes, in most of my tanks the number of fish exceeds the general rule but not all will stay in there. For frequently fish are being sold or being swapped. And because my tanks are well balanced, there's no single harm to those fish. If you're keeping the amount of fish as I do, you just need to know what to do. Otherwise, it will become a mess. And that's the challenge for a lot of people to keep the right balance and put diseases to zero. Too many people just don't know how to keep the balance correctly which also result in low maintenance. For believe me, with my 80+ tanks, I have not that much maintenance to do as a lot of people who have even less tanks.
I'm still old school when it comes to fishkeeping and maintenance. And in my opinion, that's the best way to do it for me. Back in the days it has always worked, so why not nowadays? Nowadays, the commercial market offer too much products to get things balanced while in fact it can be done in a more simple way. Also at a lot of forums (and to be honest, Facebook is one of them) or groups where a lot of youngsters are present who are raised with a lot of gadgets, are full of excitement to use and promote all the new stuff (that are actually excessive to our hobby). And from what I read so frequently, it's that group of people who have most problems with the tank, plants and fish.