The complaint is still valid. I have subscriptions to a few sites, mostly news. I get why I need to login, otherwise how would they know that I've paid. It's still a pretty poor experience, I pay for a service, and now I need to fiddle with the settings in my browser so the site I pay for can remember my credentials.
I get that part of the issue is that I keep a weird privacy focused configuration in my browsers and delete cookies when I close the browser, still it results in poor user experience, for a service that I pay for. I don't have any good suggestion on how to fix it, but it's is valid to complain about having to sign in.
It's a poor user experience because you break it on purpose. Whatever other way they can come up with to permanently identify you, you will block that in the name of privacy and keep complaining.
I don't really care about privacy from a company that already have my credit card information, and real name and address in most cases. I care about privacy from "the others", and the paid services is collateral damage. It does appear from another comment that Kagi actually thought about it and allows a token in the search URI, that's pretty neat.
You can get an access token from settings which can be provided in the URL. Set your search engine URL to include the token, and your searches just work, even in Private / Incognito.
