Alan Kay spoke about it length in many of his talks.

For example: https://www.youtube.com/watch?v=gTAghAJcO1o

Excellent video. I highly recommend everyone working in or with IT to see it.

I think he is right.

PCs and smartphone are mostly recreating thing from the past, and not the best things either. However, this isn't because we invented everything there is to invent. It has more to do with how research in computing is currently funded and how companies approach invention and innovation.

Making things smaller and power efficient IS invention, it's what has driven so much tech progress. Even supercomputers are a power problem now...

You probably should watch that video. This is one of its core subject. Kay makes a valuable distinction between invention and innovation, and what you describe falls into the "innovation" bucket. It's incremental. Yes, our cellphones are more powerful than mainframes of the old, but do we utilize them to the same extent?

So are FinFETs, Quantum Wells, EUV lithography, compact linear accelerators and all the devices necessary for shrinking just "innovation"?

What's "invention then"?

radio probably is invention .. various multiplexing techniques like TDMA, FDMA, CDMA are not ..

But aren't lasers incremental too?

With enough work one can convince oneself that each 'discovery' or 'invention' is a trivial follow-up of existing technology. DNA sequencing is in the post-laser era. Can you build a convincing argument as to why it's not new but the laser is new?

the first laser was built in the 60s, DNA was isolated in 1878.

Sequencing, not isolation. You might as well say that light has been observed since man has had eyes to see.

I've always thought - and described PC's as mini mainframes. Even the software we run on them is mainframe derived - Unix and VMS.

The mobile/tablet is truly the first "personal computer", which we've barely tapped yet. I am hopeful, but at the moment we haven't gone much beyond what we could do with very efficient punch card sorting.