There are limits to promotion at any company. Probably no limits from fresh-college-grad to the next level of software engineer (SWE-2 or equivalent). That becomes less true at higher levels. If Bob is a Vice President of Tech, reporting to the CTO, Bob may have no realistic prospect to be promoted to any position other than CTO and if the CTO is successful and not leaving, then Bob has a lack of promotion opportunity. If the CTO keeps working out, most companies would be rationally willing to let Bob leave and replace him if that's Bob's choice (and therefore want to know when he's contemplating that seriously).