"don't you think this is a sign of not being able to develop new stuff themselves"
Sure, but they are quick to buy then before they can pose a danger. The problem today is that there are several ways to make a lot of money without any need to develop innovative stuff.
For them, it's a win-win situation, small investments, huge returns. Still, they are not "arthritic" - usually they're quick enough - just their "decision making process" seldom involves innovative products - mostly is a repackaging of existing ones through a site/app and a subscription, whenever possible.