Ammo clearly seems the weakest link now in rimfire for the masses, much more than it's ever been before. Ammo has always been the weak link in rimfire at the highest levels, but today the big difference I see is that just about anyone can go down and buy a Tikka/CZ/Bergara off the shelf and it's probably going to shoot pretty darn well with match ammo. 30 years ago you didn't get that unless you spent the money for Anchutz or a few of the other target guns, or had something built custom, or you just got really really lucky in the factory barrel lottery. Most guys if they were trying to customize something it was a 10/22. 35 years ago when I was shooting competitive 3/4 position smallbore, basically no one was lot testing ammo, most folks just bought Eley Black box and figured if there were issues, it was them. I can't ever remember a coach I had talking about the importance of testing lots or even across brands. It was assumed that the higher Eley tiers were better, but no one really felt it was a concern. Of course at that time most indoor 3/4 position was shot at 50ft and outdoor at 50yds. Considering the size of most people's groups at 50 yds kneeling/standing it's highly unlikely ammo consistency was ever a significant dent in overall scores. Benchrest of course was a different story.
It's truly the "easy button" for rimfire these days. Pretty much anyone can go buy a sub $1000 CZ put descent quality match ammo through it and it's going to shoot really well at 50yds. Better than the best rimfire guns of 50 years ago, nah, but the difference is you can buy them in just about every gun store now for $500 and up, and overall they are likely easier to shoot, more adjustable, etc.
Of course the consumer has changed too and is much easier to part from their $$$. 30 years ago no one outside of serious competition folks would dream of spending over $1000 on a rimfire, now guys line up to drop $2-3k on one that are just weekend range shooters. It's like when I bought my first swarvoski gear probably back in the 2002 timeframe. You almost never saw anyone at the range with high end optics gear. These days there's not a day I go to the range where I don't see multiple several thousand dollar setups. It's like the other day when I was walking in Target and noticed they had $700 coffee machines sitting on the shelf for sale. 20 years ago, no one was spending $700 on a coffee machine in Target, now I hear new hires at work out of college that drop $1000 on an espresso machine. It's not inflation, it's just easier to convince people to drop lots of $$$.
I doubt we'll ever see ammo improve significantly for rimfire, unless they abandon the rimfire aspect of it which seems to be the real problem with it's consistency. If they do I can't even imagine who expensive it will be considering the top rimfire ammo now is pushing $25-$30 a box. I could see high end custom ammo for rimfire possibly improving extreme long range groups, but I think they'd have to go away from the typical lead/lube stuff that's been done.