Run a BalanceStats pass on vanilla weapons, and you'll see that the Smartcannon has a balance variation of +30.9%. Which is far beyond anything else at that level.
The closest gun to it algorithmically is the Moskva 11, which is less popular for its low range. After that is the AK15, which is supposedly slightly better before pricing (and it is, by one damage point, if you discount the tracking on the smartcannon. But these are +9.5% and +5.2% respectively. Remove cost from the equation and the Smartcannon is supposedly less effective than the AK15. I am dubious about the algorithm in this respect.
Regardless, even the final algorithm score reflects that the Smartcannon is simply outperforming its level,and doing it by a dramatic margin. There are also issues the algorithm isn't picking up (which explains its very close equivelance before cost to the AK15's score): Smartcannon ammo is almost valueless, low mass, and extremely common. It simply isn't providing sufficient penalty for the on-level damage, on-level RoF (which is even technically higher on-paper than the AK15), and extremely good tracking capability. Further, the price, ammunition factors, and rarity are negated by having an assured spawn in Eridani.
Level three is an important level. It's the highest level you can get in Eridani, and a good stepping stone to the rest of the game. We hand the player a smartcannon (for now) if they do the tutorial quests. This effectively renders every other level 3 (non-launcher) weapon obsolete: the smartcannon is so much better that there is very little reason to use anything else unless you're speedrunning or otherwise in a hurry, especially as it's effectively free to get hold of.
I like the smartcannon too, it's a great gun,and it's a very fun gun. It's an important gun to have. But it overperforms in a way that negates the value of other content at present, and both it and the rest of Level 3 need a bit of a look at (and possibly some more competition in core from new items) to get things balanced appropriately and spiced up. We need the rest of Level 3 to be as interesting to use as the Smartcannon,even if the current star gets dimmed a little to fit in better.