If the pilot isn't there to follow the bore and keep it in alignment, then what is it there for, IYO?
If the reamers will follow the bore and keep in alignment, why is that a problem?
It's "designed to follow the bore"...... this is(was) it's original intent BUT, it's primary useful function in the real world is to virtually eliminate chatter.
Bores are crooked.....
Bores are CROOKED.......
BORES ARE CROOKED!!!
NOT straight.
So, if you set up between centers, no matter how careful you are to find, measure and eliminate the lapping bell and THE BORE IS CROOKED, the chamber gets wallowed. And of course it gets wallowed differently every new barrel.
I've had up to 5 barrels made by the same guy, with the same reamer to essentially the same headspace AND THE ROUNDS DON'T INTERCHANGE.
SAME reamer
SAME gunsmith
SAME headspace
And
no joy in Muddville
Because HEADSPACE isn't even half the battle. I Can Deal With Headspace, I CANNOT deal with different sized and differently tapered chambers.
IME the single most important thing,
THE SINGLE MOST IMPORTANT thing in achieving and maintaining consistent accuracy over time is the fit betwixt your sizing die and your barrel(s)
To do this you absolutely MUST be able to make chamber after chamber identically.
This is specifically why I bought a lathe and started doing my own work. I own 7 different 6BR chambers and have 5 different dies and STILL some of them are not matched. Thousands of dollars spent on crap.
Barrels that CANNOT shoot to potential lest I spend another 350.00 and get ANOTHER useless resizer.
I now have zero problems getting chambers identical, brand to brand, action to action, gun to gun.......because I DO NOT use the pilot bushing to steer the reamer down the rabbithole....