For a Mac workflow that involves opening, editing, and moving remote files, I want to avoid turning each small change into a separate file-management task. That is the situation I have in mind when comparing a dedicated transfer app with access through Finder.
The useful distinction is not which app has the longest feature list. I would start with where I want to do the work. If I mainly need access to a remote file while doing something else, a separate transfer window may be unnecessary. If moving files is the job itself, having a dedicated place for that work makes more sense to me.
Put remote access where the work already happens
For the Finder-based route, the CloudMounter approach is to mount FTP, SFTP, and cloud accounts so they appear in Finder like external drives. That changes where you interact with the files rather than asking you to keep returning to a separate transfer manager.
You can open, edit, and move remote files through native Mac windows. For the workflow I am considering, that is the main reason to look at it: access stays in the same file-management interface instead of becoming another application to manage.
I would keep that benefit fairly narrow. Appearing in Finder is useful if Finder is where you prefer to work. It is not, by itself, a reason to replace a transfer app that already fits your routine. I also would not take the external-drive comparison as proof that every aspect of working remotely is identical to working with a local drive. The point here is the interface and the way you reach the files.
Keep a separate transfer step if it serves a purpose
If you prefer to move files back and forth manually, the ForkLift option belongs on the other side of this comparison. A dedicated transfer setup keeps that activity separate from the rest of your file work.
Along the same lines, the Cyberduck option is worth considering when manual transfers are what you want. I would not choose between those two based on the Finder argument, because that argument answers a different question: whether you want a separate transfer workflow at all.
My starting preference would be Finder access for opening and editing remote files, and a dedicated app when I want transfers to be a distinct task. That is a workflow preference, not a performance ranking.
I would change that preference if a trial with the actual accounts and files showed that Finder-based access made opening, editing, or moving them less straightforward than using a separate transfer manager.