Has the author of this article ever used a custom ROM? There are so many free alternatives for these apps out there. If I remember correctly, LineageOS ships with their own version of Dialer/Messages anyway. I usually replace them with the versions of SimpleMobileTools, which work just fine.
The main difficulty for custom ROMs are not these standard apps. The real issues are bootloaders which cannot be unlocked, undocumented binary&buggy firmware blobs, SafetyNet, Google Play Services, and so on. Just look how Google effectively broke the AuroraStore App recently. It's getting more and more difficult to use Android without a Google Account.
The main difficulty for custom ROMs are not these standard apps. The real issues are bootloaders which cannot be unlocked, undocumented binary&buggy firmware blobs, SafetyNet, Google Play Services, and so on. Just look how Google effectively broke the AuroraStore App recently. It's getting more and more difficult to use Android without a Google Account.