Every aspect of multi-player is a grindfest, want weapons? Grind tickets on other weapons. Want badges? Grind multi-player. Want a bigger locker? Get to level 30. Want to get more tableturf cards? You guessed it.
Doesn't help that FOMO is sprinkled in with fests that are still just 48 hours, the catalogs, the challenges with unique rules that you arent allowed to enjoy with a group of friends and even big runs are subject to that. Speaking of big runs. Egg lag being worse, performance drops at launch on some maps, grinding to get scales, (an issue that was alleviated an insane 2 years after launch) no checkpoints, (they were added a year after launch(they were in base game splatoon 2)) still not being able to pick from all difficulties available even in private matches (maxes out at 200% when the max is 333%)
And other mechanics introduced to artificially bring back players, the daily shellout machine pull, the 1st win exp bonus per day.
Map related bugs like clipping in the rotating walls on wahoo world, which got patched out after being discovered in S2, returned in S3 at launch. Map design is generally more linear. There's no 3rd kit. And more things like 12hrtz refresh rate making only 1/5 input on your end mattering (movement wise) but the kicker is that squid surge got introduced and rewards guesswork if you're not parrying a bomb which is predictable. Like the scenario that was shown in the trailer of doing a squid surge against a charger, that would be frame perfect on 2 players end, for the one shooting and the one parrying.