It seems like everyone had a "tack driver" muzzleloader today. Just ask them.
There are so many different contributing factors to shooting tight groups, especially consistently, they're hard to count.
The majority of the time, the shooter themselves are more problem than the rifle and load. To shoot exceptionally tight groups, the shooter has to do everything EXACT each time he/she loads the rifle and holds the rifle.
Even the slightest difference in hold of your trigger hand matters. Grip force matters and changing it can certainly affect group size. Trigger quality matters. Trigger finger placement on the trigger itself matters. Mounting to the shoulder matters. Shooting tight groups takes practice, even more practice for long range (200yds +) shooting.
Mounts, rings and certainly the scope matters. You don't actually witness many shooters making tiny size groups, even at 100yds, with a low power variable. Certainly quality components matter.
Consistently shooting tight (1" - MOA or less) groups at 100yds isn't as easy as some might suggest with their "tack drivers". It takes a LOT of practice, hundreds if not thousands of rounds down range, especially at long range distances.
There are just some shooters that are just naturals, while others struggle to some degree, be it age, eye sight, or components.
Lack of complete confidence hurts more shooters themselves than anything. Even the best of top shooters, will have a PP day if they dwell on a bad shot or a single days shooting. NOT thinking or remembering a bad day or shot, it taught in all the shooting schools. A shooter has to concentrate on the immediate moment and shot, not a single bad shot or day. Make the rifle an extension of your own body, not a separate object.
Speaking only for myself...... Its my intent to shoot 1" (MOA) or less groups at 100yds. I have complete confidence in the rifle I shoot or rifles I've used before. With that confidence level, it only leaves one variable...... me the shooter. Some days I get the bear, some days the bear gets me at 66 years young.