From what I've heard part of why CPAs/Accountants are reluctant to learn some other system that isn't QB isn't because QB is good for them, but that they have decades of accumulated cruft like Excel macros and similar hacks to try to make okay double entry lemonade from QB's awful single entry lemons. It's relearning/rebuilding all that that they don't want to do, even if they don't directly realize a lot of their pain stems from the fact that QB is just bad at its job (and has been for a long time).
(Disclaimer/source: Way back in ought six, I was an intern on Microsoft's attempt at the space in a product called Small Business Accounting and then briefly Office Accounting before it died. Among other things SBA chased after CPA/Accountant buy-in and from what I heard nearly had it, as it was proper double-entry for one reason. The takeaway that winning over CPAs/Accountants alone isn't sufficient is mine based only a peripheral reading of what went wrong with that project and what I managed to gather of why that product didn't exist any longer by the time I graduated.)
Now I just use quickbooks. I have never had any issue.
Gnucash is great and works fine for personal bookkeeping, but I wouldn't suggest it if you have an accountant.
Many of us here are way more expensive per hour than our accountant ;) -- but to your metapoint that the accountant is more expensive than a new quickbooks subscription, that probably remains true even in the face of the price hike.
But I do agree, when I had just W2 income and a mortgage it was no big deal to do them myself. I definitely wouldn't use an accountant if my taxes were simple enough to handle it. They're just not that hard.
For instance, in the U.S., certain tax filings and other types of official paperwork require businesses and individuals to give permission to authorities to contact CPAs directly.
In addition, tax laws are also very local, including state regulations (50 U.S. states + territories) and sometimes municipal and county regulations. This requires a level of expertise that few overseas-based bookkeepers would be able to work with.
My accountant has access to all the data I put in there. Mostly feature parity with Quickbooks.
Mostly free to use (I have never paid a dollar for the expense tracking part)
https://plaintextaccounting.org/
I haven't used these solutions much, just know about thier existance.