The common model: a plan limit on the number of BMs
Many media-buying tools tie plan price to how many Business Managers you connect — more BMs, higher plan. The logic sounds reasonable: more BMs usually means more clients/support needs. But for a team that spreads BM risk on purpose (not putting every account in one Business Manager, so one restriction doesn't take down the rest), that kind of limit penalizes exactly the cautious behavior — you pay extra for diversifying correctly.
Why a BM limit isn't technically necessary at all
A Business Manager is Meta's organizational unit, not a resource that's expensive for a service to serve: connecting one more BM with a System User token is the same operation as the first one, with no added infrastructure load comparable to, say, the number of actual launches or ad accounts (which genuinely need compute — a launch queue, a step-by-step log, statistics).
What's worth limiting instead
It makes more sense to tie plan price to what actually scales load on the service: team seats, connected ad accounts, launches per month. A BM by itself is just a container for accounts and tokens — limiting it separately is an artificial constraint that doesn't reflect the service's real cost.
What this means when choosing a tool
If you're comparing bulk-launch tools and see a "BM limit" in the pricing grid, that's worth asking about directly — what's actually behind that constraint technically. If the answer boils down to "that's just how the pricing evolved" rather than real infrastructure load, it's probably just a way to raise your price as your team grows, not a reflection of real costs.