Repackaging public data is big business. It's often easier to pay someone who has already done the work than reinventing the wheel yourself.

It's public data, but it's time consuming to get the data "ready for analysis". Instead of doing this prep work yourself, you can pay someone else (in this case Coinbase) to do that part.

source: I run a competitor to Tracer (https://luabase.com/)

I'm assuming that somehow coinbase is correlating it to wallets somehow, and tht might be the valuable part

Yeah I guess that's not really just public data anymore.

Cheaper than hiring in house expertees?

Likely, yes. A decent data engineer is probably six figures minimum, whereas data is cheap.

expertise

The only reason to say this would be to deceive the audience. I can see no other reason.