The seeming truth of the matter is that most wifi devices just have terrible radio gear. The mesh units said they only had so-so signal in my house, but they just had so very much better radios. I don't think we had a single client device anywhere would ever dip below 300mbps if it's radio could get that high. The backhauls for most mesh gear are incredibly good. I would put away your fear, in most cases. These products work incredibly good. Sometimes you may indeed need to add one more node to make all your problems go away - to make the hops physically shorter, to give the backhauls shorter/lower-interference links - but that's much much easier than dropping ethernet, is such an easy chore to deal with. Any potential problem can be solved by adding more nodes, creating a denser / less long distance mesh.
If you really demand on gigabit (really, post-gigabit; mesh can definitely do gigabit) everywhere, yes, you may need to raise your spend a lot, and use 2.5Gbit ethernet APs that can bandsteer among themsleves. Frankly I think this is kind of a suckers game for 99.99% of people. The mesh products are amazing. Their latency & responsiveness is incredibly good, the bandwidth far more than adequate. Many have very reasonable costs, where-as most multi-AP solutions cost unreasonably more for no reason other than market-segmentation-exploitation.
Ideally the WAN access is not "at one end" of the mesh, but even if it is, I think it'll probably be solid for most folks in most circumstances.
When you don't run any ethernet cabling, mesh network device placement is critical because the back-haul needs to get an adequate signal to the originating device as well as provide good coverage for its area. The construction materials of the home have a big impact upon what works and what doesn't.