I have both: Hydraulic Disc on the "big" gravel bike and mini V brakes on the folding gravel bike. the rim brake does not offer good braking performance and frankly, when you go down a twisty steep hill over 40kph on loose surface,you need to be confident in you brakes... V brakes/cantilevers do not cut it.
Now, the issue about hydraulic, I can understand that some people can get a little worry about the maintenance of the hydraulic and there is a argument that if it fails in a remote area, it will be a pickle however, it is not a reason to rule out brake discs. if the issue is the hydraulic system maintenance, then, there is always the next best option: mechanical brake discs. a bike setup with spyre calipers, good disc and very good pads will be better the crappy rim brakes and the setup/maintenance is as simple if not simpler than rim brakes.
if you look at the "beginner " gravel bike like cinelli Zydeco lala, canondale topstone 3 etc. they tend to be fitted with shimano Sora groupset and mechnical road disc brake 160mm front/rear or SRam Apex or microshift mechanical disc.
These bikes work well and brake better than V brake/cantilever stuff.