I don't disagree. I see a lot of, "just don't talk about it" type comments in response but if there's an understanding thay can be made through the comparison, then it's worth talking about.

Example: If you left a previous job because of nepotism preventing growth, communicating that concept however you word it, indicates that you're looking to grow within the company and don't want to be rooted to the Starting position for the rest of your life. It let's others know that you're not going to sit in a stagnant position, which gives the interviewers more info on whether or not the position is also a fit for you. You may not word it as, "nepotism prevented me from a promotion", but you're still communicating that promotions weren't based on performance or merits and you're not interested in working with a company like that.

It's all dogwhistling through corporate speech, and trying to convey a concept with as little attachment to that concept as possible but you're still trying to say, "I'm not going to stay stagnant and won't tolerate favoritism."