Well, I did say I'd make a longer post, so here goes...
As I mentioned in my previous post, the chief (but not sole) reason why I dislike Dynamax is that it doesn't act as an equalizer in any circumstance. The Pokemon who benefit most from Dynamax were already really good before its debut, and lower tier Pokemon that aren't really viable are not going to be lifted into viability by it. There's simply no reason to use them when you can Dynamax a better Pokemon altogether. This is part of the problem with Dynamax, and it stems from the one aspect that people seem to praise the most; its inclusivity. Almost any Pokemon can Dynamax, but only a select few can Mega Evolve. On the surface, this makes it seem like Dynamax is a great idea. What if my favorite Pokemon isn't viable by itself, and wasn't graced with a Mega Evolution? Surely Dynamax is a better mechanic for me, as it benefits all Pokemon? Well, no. Dynamax may benefit all Pokemon equally, but the playing field wasn't equal to begin with. Generally, the same Pokemon are still going to end up better than the others.
Now let's take a look at Mega Evolution. While Mega Evolution may be much more limited in its distribution, it is a huge buff to nearly all Pokemon it does get distributed to. Unlike Dynamax, which offers a uniform HP increase and powered-up moves to all Pokemon affected by it, Mega Evolution offers stat overhauls and possible new typing and abilities to its recipients on a case-by-case basis. This makes it possible to take Pokemon like Beedrill, Kangaskhan, and Pinsir, who are competitively garbage, and transform them into actual threats. While there's no guarantee that a Pokemon I want to use receives a Mega Evolution, if one does happen to receive one, it's almost guaranteed to be a viable addition to my team. Even the more obscure Megas such as Abomasnow and Camerupt have uses in the more inclusive formats.
The fact that Dynamax only truly benefits Pokemon that were already viable is just one issue I have with it, though. Another is that Gigantomax is almost completely pointless as a mechanic. When it was first revealed, I was sure that Gigantomax forms would receive some kind of stat changes akin to Mega Evolution, if not as drastic. They didn't. The only difference between Gigantomax and Dynamax is access to an exclusive G-Max move... which is usually inferior to its regular Max equivalent. Why would you ever Gigantomax your Charizard so you can use G-Max Wildfire when you can Dynamax it and use Max Flare, whose effects are far better in nearly every circumstance? Save for a few exceptions such as Gengar and Copperajah, why would you ever use most Pokemon's Gigantomax forms over their Dynamax forms? One possible solution for this would have been to tie G-Max moves to specific moves (such as Blast Burn for G-Max Wildfire), allowing you to use the standard Max Move of that type if you wish, but even then, you're just left with a fancy looking Dynamax Charizard.
Another problem with Dynamax is how heavily biased the mechanic is towards offensive Pokemon. I had a similar problem with Z-Moves, and if I'm being 100% honest, even Mega Evolutions tend to be more inclined towards offensive Pokemon than defensive Pokemon (but at least Pokemon such as Mega Sableye, Mega Slowbro, and Mega Venusaur existed to give you some defensive options), but Dynamax is by far the biggest offender in this regard. While offensive Pokemon have access to a myriad of high-power moves with a variety of different effects, on the defensive side of things you have exactly one move; a reskinned Protect. No recovery while Dynamaxed. No support moves while Dynamaxed. The only thing you can do is be a glorified meat shield for your opponent's Dynamaxed Pokemon to wail on for 3 turns. While defensive Dynamaxing is a legitimate strategy in some cases, it's more of a reactive strategy than a proactive one, whereas a defensive Mega Evolution such as Sableye can be used very proactively. The very least they could have done would be to have given us a Max Recover that recovery moves transform into.
In general, I really just wish they had stuck with Mega Evolution. Z-Moves were a farce but at least they had some positive aspects as well. I can't really think of anything good to say about Dynamax. It's not creative, it's not healthy, it doesn't bring any sort of balance to the metagame, and it seems in general poorly thought out. I seriously hope they reconsider the decision to axe the only gimmick they've introduced so far that actually brought some balance and variety to the metagame.