Does that mirror your experience working in DD?
Failures in the other areas are root causes and more fundamental issues.
Second, every client has different priorities, but in general, they want to know what the potential risks are of tanking the investment, and what they need to do to make sure this can't hapen. PE firms aren't like VCs... they don't want a 1 in 10 chance of unicorn, they want a 90% chance of a solid return with zero chance of losing the entire thing. When you're spending $50M to a $1B, a low-but-avoidable risk of disaster is not OK. Finding those is our number one priority. If the code is not awful, then the people, process, and org risks are much more likely to do this.
I'm one of the first to say tech debt kills companies - I've literally seen it. But.... dysfunctional organizations kill companies worse and faster. And those are much easier to sniff out in two days of interviews.
I work in technical diligence, we assess companies getting purchased, getting ready to exit, raising money, etc. I've done 50+ myself, read reports for hundreds more, and Crosslake (my employer) has done thousands. This is not our experience.
Overspend on dev team is occasionally an issue. Key person risks, tech debt, and other symptoms of lack of expertise are frequently serious issues. (No amount of juniours eliminates key person risk on a senior, only a similarly expert senior does). The companies I have seen that made policies of hiring smaller teams of the best people they can find and paying them well were, in general, kicking ass.
I would argue this article has it completely backwards. My opinion, based on anecdotal (because I didn't run stats on it) but much larger sample size is that the difference to your company over the long term of senior vs junior dwarfs the difference in cost. We are constantly saying "hire more seniors in X,Y,Z". We are rarely saying "cut dev spend".
My advice: for your core offering, buy the best devs you can and make them happy. For all the peripheral commodity stuff (the "not rocket science"), outsource to Eastern Europe and have a full time senior based locally who job is to run that team, interfacing with their lead and managing integration with your core.
Especially right now. Preferring juniors when the market is full of freshly unemploye ace seniors would be terrifically stupid.