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The meta sucks because all the counter-plays specifically require you to prepare for the single event in which your opponent randomly Dynamaxes and sweeps your entire team.
The mechanic itself isn't fun to fight against since each Max move can give random buffs and cause field-effects, practically negating any strategic plays you can make.
The limited dex also prevents interesting team builds, as if you don't have the exact team setup as everyone else, you ARE going to lose.