First off, Of course the shops will want to sell you rocker arm stoppers. They make money on them.
People who do swaps will want to sell you rocker arm stoppers. They will make money on the labor to install them.
I tell everyone I come across that rocker arm stoppers are a waste of money. They do nothing except aid in broken rocker arms.
I have turned 9k+ free revving my engine and have not broken or popped off a rocker arm. Rocker arms will fly off when you get valve float or when your lifters collapse. You should spend the money on better valvetrain, and not the 60 or 70 dollars on rocker arm stoppers. That can be the difference between a budget valve spring or a good valve spring (Peak Performance Stage 2).

By the way :

Mazworx also do not run rocker arm stoppers in their 11,000 RPM drag SR. That is higher than most of you see when you mis shift from 5th to 2nd with a piece of trash B&M shifter. So if they don't run them, and don't have problems breaking rocker arms.. hmm.. maybe the problem is somewhere else. Just maybe.

I will continue to stand by the theory that if you're operating the valvetrain outside of its original range, the hydraulic lifters become very unstable and subject to failure. I mean, considering every japanese race SR i've ever come across (numerous at D1, Formula D, SEMA, etc) all of them had solid lash. Oh and GTiR's run solid lash and don't have rocker stoppers either. The only way GTiR's break rockers is from valve float as well.

with the proper valve springs and the proper lash assembly there should be no need for you to ever do rocker stoppers.

on another side of things, if you don't run rocker arm stoppers, you'll simply pop a rocker arm off. If you run rocker arm stoppers, your rocker will be pinned in place and will be broken in half from the cam lobe smacking into it.

What are you guys revving to again?