I don’t think there was any dig implied. And I will second that it will add to self esteem. Specially during discussions if you have more understanding about the code you will have both better contribution and take away
Sure, when you succeed in understanding someone else's legacy codebase, it builds self esteem. When you fail attempting to do that, it does the opposite.
I have inherited projects where I just could never understand what they were thinking well enough to make the service good (not running out of memory and crashing). It was very humbling; I still sometimes wake up in the middle of the night with things I wish I'd tried, but the assumptions of how it all worked was just scattered throughout a bunch of files and the assumptions of everything was just not how I'd do it.