The ATF is one of the biggest pro-gun anti-gun positives that exists for our benefit.
No that does not contradict itself.
Because the ATF exists solely to enforce a limited number of laws, primarily guns laws at this point, such gun laws are not a priority of other agencies.
The ATF is the gun control enforcers.
The ATF is disliked by a decent percentage of the population, and Congress restricts the budget of the ATF far more than they restrict the budget of an agency like the FBI.
Since the ATF exists it allows pro-gun influences to reduce the funding and budget of the ATF, in essence reducing the extent of enforcement of gun control laws.
This forces the limited budget ATF to prioritize its efforts on a small number of operations and a limited number of prosecutions each year.
If you eliminate the ATF the exact same type of agents involved in activities you dislike will be working for a new agency, agencies that will then prioritize gun control laws they currently defer to the ATF to enforce.
These agencies will have far greater budgets than the ATF ever has, so when they have an anti-gun Director or President tell them to make gun control a priority, far more prosecutions and harassment of citizens and FFLs can occur than it can under the ATF.
So the ATF helps gun owners more than it hurts by being the hated agency nobody likes to fund very much.
Because that agency exists to enforce gun laws other agencies leave most gun control law enforcement at the federal level to the ATF.
This results in limited enforcement, low budget for enforcement, and in general less extensive gun control efforts at the federal level. (Leaving most gun related prosecutions to the state level.)
Gun owners may seriously regret the lack of the ATF when suddenly the other federal agencies focus more on gun laws instead of leaving it to the ATF.
You can be sure many existing ATF federal agents will be transferring to head new gun control divisions in other LEO agencies. They will be the most qualified and well versed on gun laws after all. They will then operate with a budget the ATF could have never dreamed of. They will be able to prosecute far more people over things like 18 USC 922(r).
At this point the best scenario is a hated underfunded ATF, and trying to reduce existing gun control laws legislatively or their scope judicially.
No ATF would likely be a worse scenario.