the biggest hurdles the chargers have to overcome is the issue of the loss of mobility and coverage
in a vacuum, the chargers actually have better mobility than shooters, because with a fully charged shot you can lay down a straight path to swim up as opposed to shooting, swimming, shooting, swimming, repeat with the shooters. however, because of splatterhopping, splatdashing, and all the other undiscovered movement techs in this game, the shooters have some absurd mobility that rollers and chargers can't compete with. it creates an interesting dynamic with the roller; you can sacrifice mobility and killing power for ink coverage, which is an insanely helpful asset to your team, but a disadvantage to yourself. but the chargers give up ink coverage and mobility for killing power, which is helpful, but... just think of this
you could run with a charger and help your team by assassinating targets from afar, or you could pick a shooter and help them directly and cover more of the map in ink and get back into the fight faster. on some stages and team compositions, the charger is definitely a great choice, but in most circumstances you can just use a splattershot instead and not miss much of the benefits chargers bring to the table
my opinion of chargers have gone from competitively unviable to certainly valid choice, but the fact it's going to have trouble competing with other weapons, that's for sure