Consider this: every day on ProductHunt, we see dozens if not hundred new apps pumped out. How many of those succeed? Not very many. Why?
Each and every one of those apps was designed to solve a problem. So, why is there so little demand? It's because users already have another app/spreadsheet/website/solution/process that does something too similar and because their existing solution is good enough.
The fact that so many apps are being produced and fail to see traction is an indication of massive oversupply of solutions and talent. It's just too easy to produce yet another app, and so everyone does. this inevitably, must lead to an oversupply of solutions.
You're exactly right. Outside of deep deep tech (e.g. self-driving cars), you'd have to really, REALLY dig deep to find one or two startups that failed because of lack of technical talent.
Now consider how many startups failed because of lack of customer demand - nearly all of them.
This isn't just an indicator of an oversupply of talent, it also suggests an oversupply of capital. Cheap money lets you find talent, but it doesn't guarantee a path to a profitable business.
You are wrongly correlating apps launched on ProductHunt to be representative of all problems being solved. If I were to describe one word for ProductHunt launches, then it would be "sensationalist". Most of the apps being launched there are moreso trying to go viral than solving a profound and/or boring problem. The YC launches are probably more representative of the landscape and most of them have never had a ProductHunt launch.
I don't see this at all as related to oversupply of solutions and talent. It's a darwinian structural feature of many of these domains that a very small number of winners will beat out all other solutions, and if the problem is valuable a large number of candidates will compete for the chance to be a winner.
Likewise with talent, roles are not fungible. If I'm engineer #5 at one of 100 photo-sharing startups that's a totally different proposition to being engineer #500 at one large photosharing company. A different sort of candidate is going for that second role and you actually need somewhat different personality and skills. That implies a really different competitive dynamic as well.
I think there are more information problems out there than software engineers.