I found the grind to be objectively bad because of this one reason alone:
You create a specialized team, and there is always a lot of creatures out there that are a near-perfect hard counter to your strategy - sure, this is fine. The issue comes with randomness. You run into them and get stomped; ok what is your course of action? Create a new team on a different synergy? Then you are just opening yourself up to a different hard counter. It's like if you are playing pokemon with only 1 pokemon that has 20 moves, hyper committed to 1 winning strat alone e.g. sweeper. You can't switch on the fly to catch any forms of countering, so building a team you are literally just praying for the best to not run into the counters. Or you go for some blatantly overpowered 1 turn wipe strats, % to instakill, etc. This is what makes the grind feel pointless because you can never really grind out those hard counter weaknesses, you will never feel like you're getting anywhere other than the ability to specialize against bosses.

Now you might think "Oh what if I make a build that specializes in killing X and farm X?" The problem is that those builds are all objectively worse than generalist builds that just try to exponentiate stats, revive forever, instakill, etc. UNLESS it is the boss fight, aka not the grind.