This was one of the reasons. Also, how does a small company provide a laptop to remote workers across the globe in just about every locale and tax jurisdiction, many with specific job requirements and most with Strong Opinions?
There are many reasons not to work for Canonical, but the opportunity to pick and choose your own hardware rather than suffer what someone else thought your would need seems an odd choice.
Not saying this is their reasoning - and if they're not too cheap, it would surely be better for tax purposes to buy your employees computers than pay them the equivalent in cash - but it's a reason at least.