I do think these aggregated services are a net benefit to the fintech ecosystem overall. However, any service that uses a Plaid type service still could be selling transaction data to third-parties. For instance, Acorns:
>>> Acorns uses Plaid Inc. (“Plaid”) to gather your data from financial institutions...
>>> Acorns and Empyr will use transaction information from your Acorns debit card in connection with the Found Money Plus program as follows:
... to provide participating merchants or Empyr aggregated and anonymized information relating specifically to registered card activity solely to allow participating merchants and Empyr to assess the results of their campaign(s);
That means they are only sharing data from your Acorns debit card, not your external bank accounts. The Plaid part is separate from the debit card/Found Money Plus part.
You also omitted a key quote:
>when you activate your Acorns debit card, you will be asked to enroll in Found Money Plus, a card-linked offer program offered in partnership with Empyr.
The Found Money Plus program is only for transactions on the Acorns debit card, and it is small bonuses for specific spending, for example, 10% cash back at Starbucks. It looks like a company called Empyr organizes these campaigns for the card link offers.
The Acrons debit card is also optional.
If you're getting cash back on a transaction you know the price is sharing your purchases, this concept isn't really new.
https://www.acorns.com/privacy/
>>> Acorns uses Plaid Inc. (“Plaid”) to gather your data from financial institutions...
>>> Acorns and Empyr will use transaction information from your Acorns debit card in connection with the Found Money Plus program as follows:
... to provide participating merchants or Empyr aggregated and anonymized information relating specifically to registered card activity solely to allow participating merchants and Empyr to assess the results of their campaign(s);