You sure that's not just for GPL? I worked at a place that had a strict no-GPL policy due to the legal risks of non-compliance. LGPL and MIT software was fine though.
"The legal risks of non-compliance" are the exact FUD the old Microsoft spread. If someone doesn't follow the GPL then they don't have a right to reproduce the software and can be liable for copyright infringement, which is the same as any software license proprietary or otherwise.
That someone wouldn't be liable if they distribute the source for their modifications doesn't increase the risk, it decreases it by providing an alternative to paying damages for infringement that they otherwise wouldn't have, since the GPL author will typically accept compliance in lieu of monetary damages.
Commercial licenses are long and frequently contain terms that are unintuitive or ambiguous which are trivial to violate when most of the employees using the software aren't aware they exist.
And the easiest way to violate them is simply to have installed more copies than you're licensed for, which is an issue the GPL doesn't have.
Trying to figure out exactly which production licenses were needed to be in compliance used to be a recurring nightmare back in the day when I did B2B bespoke system rollouts. A licensing guide, not the license itself but the document trying to explain which licenses have to be acquired under which circumstances, could run well over 100 pages. Microsoft had licensing specialists that the channel could call for help, but if you called them twice or more for the same case you would never get the same answer twice. It was that complex, their own specialists couldn't make heads from tales on it.
>Microsoft had licensing specialists that the channel could call for help, but if you called them twice or more for the same case you would never get the same answer twice.
Do they preface with a "I'm not a lawyer" disclaimer and claim that anything they say is non binding?
That someone wouldn't be liable if they distribute the source for their modifications doesn't increase the risk, it decreases it by providing an alternative to paying damages for infringement that they otherwise wouldn't have, since the GPL author will typically accept compliance in lieu of monetary damages.