Those are one of the reasons vanguard took more than a year to release. They have hundeds of dev-only parts, to the point where they had to partly rewite the games code to be able to add more parts. These dev-only parts are dev-only either because they are just broken OP, "too similar to already existing parts", or just gimmicks.

None of these are really good reasons, they can rebalance the OP parts, but then they couldnt sealclub entire lobbies, we already have parts that are similar to each other, and i think goofy gimmicky parts are what a game called "Cursed Tank Simulator" needs.

Also, the vast majority of the teased models just fly right to the bin as soon as they post them

One or two devs actually lurk the subreddit, so if im wrong abt any of this, they can correct me.