When one of them really is enough
We are not going to pretend everybody needs everything. Two honest cases.
Profile only, for now
A brand new local business, working from a van, needing to exist on a map this week. Claim the profile, fill it in properly, get some real reviews. That is a genuinely good use of an afternoon and it will bring in work. Treat it as a start rather than a strategy: the ceiling arrives sooner than people expect, usually the first time somebody needs to know whether you do a specific thing.
Website only
A business with no local component at all. If your customers are nationwide and nobody is ever driving to you or you to them, the local layer is not where your effort belongs. The site, and the technical foundations under it, are the whole game.
Where "one is enough" stops being true
The moment you have local competitors. If somebody else in your area has both, and both are looked after, you are being compared against a business that can be found and makes a case for itself. Having one of the two is not half as good. It is being visible but unconvincing, or convincing but invisible.