Ask HN: Is it necessary to set SaaS pricing based on amount of database rows?

Say you have a e-commerce SaaS with pricing like this: - $150/month up to 10k inventory items - $200/month up to 50k inventory items - $250/month up to 100k inventory items - $300/month up to 200k inventory items

Is that necessary from a technological point of view, or is that strictly a business thing that is trying to use the pricing tiers to help with revenue? Seems like a case of artificial scarcity? It seems like limiting the number of items isn't necessary and the costs of maintaining a large database(s) are relatively fixed as you scale up, so why not offer everybody the same amount of items?

I know that a database can only hold so many items, but are there problems with scale where too many items will slow things down? If you only have 500 tenants, that's not a huge issue? The issue is a lot tenants, right? (I guess it matters how you're doing multi-tenancy.) Presumably if you're big enough you can shard and all those tricks that I'm vaguely aware of but never had to deal with.

What am I missing? Note that I've never worked on a large database so I'm quite ignorant — please be gentle!