You're thinking as if it was Windows. In enterprise environments, companies control a set of proxy repositories and whitelist/blacklist packages.
If you're a dev and need a specific package (or set of packages) that aren't listed, then you can request it through a ticket.

What do companies gain from a full Linux environment?

• Better integration with services (if it's already a linux/unix shop).
• Cost reduction from licenses (although an increase in training/in-house expertise costs)
• Machines will run supported as long as the silicon stays welded.
• Better security if implemented right.
  (A big issue of Windows is that for running secure you need to cut a lot of it, which generates shadow IT).

However if not done right, there's a long list of head-aches, including some software that's no longer compatible and has no real professional linux option (design suites, SCADA/ICS, CAD software, etc).
Even if there's a similar tool, it's highly possible that there are trade-offs that will require a lot of investment.

In most cases this gets solved in two ways:

• Designers get a Mac so they can stop whinning and IT churns a solution to integrate all the outdated stuff running on that OS with the rest of enterprise services.
• Windows stuff that doesn't require a beffy computer gets deployed on a VM with RBAC integrated with the company's IDP.