Mobile gets the benefit that when it really started to take off, they more or less came to a few standards that allowed for more open and cross platform support. Just about any device you buy now can get access to email from almost any back end server, regardless if the server is Microsoft, Un*x or the like. This was a great boon for Apple as people were able to pick the device that they wanted and have it supported.
Unfortunately, This isn't how things work in the rest of Corporate. Especially in regards to proprietary applications. Many large corporations and enterprises run very proprietary software, or, heavily modified open platforms. For Example, Microsoft Great Plains is a heavily modifiable, and customizable Accounting and finance platform. Guess what, it will only run on MIcrosoft. our Platform for example uses a very particular runtime that will only run Windows or Unix only.