I think it's more the MBA-fication of the industry. There's no time for exploring and tinkering, it's all just chasing after the next ticket/okr.
Under that model, 10% of your time is completely up to you (within reason) to work on things that aren't your main project or scope.
Works out well for R&D or more open ended positions, since you can have the flexibility to explore hunches without having to justify a whole project around it.