Should every computer and system in the company have the same browser and applications? Yes, they most certainly should. (Aside of course special cases where required.) The reason I'm on the yes camp has to do with maintenance, security and keeping systems updated.
Computers at the company do not belong to the employees, letting them install whatever they want leads to problems. It further complicates the process of updating the software with new security updates. Do we update every single browser (or other application) one of the employees might have installed? No. Most virus and other nasty software gets on a company's computers because of lax software rules. Giving their employees freedom to do whatever they like on their computers.
Another complication when it comes time to update hardware, or reimaging (easier then reinstalling everything from scratch) computers. Do we keep a dozen different images for every employee? For me it is a maintenance and security nightmare. Users should not have the privilege to have any access beyond what they need to work. These computers do not belong to them.
For me it all comes down to: these computers are for work. So why do we need all of this software on them? It is just excess baggage (adding to potential security vulnerabilities) that we are wasting our time on trying to keep it all updated.