This statement, "If it's free, I'm the product" is becoming less and less relevant because, "Even if it's not free, I'm usually the product anyway"

Think Comcast, Verizon, various Android phones, various modern TVs, etc.

Okay, granted many companies do it, but you're still dodging the parent comment's issue about this specifically. WHY is it free, WHAT are they doing?

Also: Apple.

Do you have any citations for that claim? Anything I can search for?

Admittedly I was a little concerned by that, but since I already use them for credit monitoring I didn't feel like I was handing them all that much more information. Better to give them a little more info, than involve another company who may still use my info even after I pay them.

I do like they're at least pretty transparent about their business model:

https://help.creditkarma.com/hc/en-us/articles/202414090-Is-...

https://www.investopedia.com/articles/personal-finance/01081...

https://www.moneyunder30.com/credit-karma

Mate, even when you do pay for services, you're still getting your data sold to third-party vendors.

So you might as well utilize companies that provide an actually good product.

Do the offline/desktop versions of TurboTax, etc do this? Not arguing, just surprised

The IRS requires any tax filing software to get your permission to use your information for anything other than filing your taxes. In the case of TurboTax there's a contract they present at the beginning that authorizes them to use your information for marketing. If you decline the contract then you can still use their services and they're not able to sell your information on unless it's related to filing your taxes.

At the very least, they can’t violate IRS §7216 without your explicit consent, which they ask for with the default sync to their parent company. And for now that isn’t required to use their filing.