I think that's Google hemartia. They execute really well initially, but falter on maintaining and nurturing ideas and products. The internal incentives regarding promotions and pay amplify the problem. Maintaining or improving a product isn't as impactful to one's career as creating an entirely new one. They have a half dozen chat apps because they unintentionally created an engineering "crabs in the bucket" situation. Not to say they are anywhere near as bad as the companies who do it on purpose a la stack ranking though.

I think another important factor is that what's a viable business to one party isn't worth it to Google simply because they can use that engineering talent more effectively in a monetary sense elsewhere. Even spinning them out doesn't make sense from a numbers perspective. The big problem with that is that they utterly ruin the landscape for everybody who isn't Google and who would operate just fine if it weren't for the size 20 boots giant that tramples all over the space before giving up on it.