If you define “end user” as “institution with enough profit to hire a developer”, then yes, it’s a tautology that they can hire a developer. But that’s a minuscule fraction of end users. The person who buys Quickbooks off the shelf at Office Max isn’t hiring any developers.
Non-developers take advantage of it by hiring a developer; it's essentially the right to take your software to be serviced by someone other than the seller.
> Traditionally the FSF advocate will say something here about end users hiring developers to modify software for them, but in reality that’s economically ridiculous.
It's perhaps ridiculous for non-wealthy individual end-users for software that isn't integral to a profit-making business, but it's quite common for major open source projects to see most of their contributions being from institutional end-users who have hired developers to address their own needs with the software.