"Need" is too strong. Without going into the arguments against DoH, we don't "need" it, because there is an alternative: run your own recursive DNS. That should be something that a consumer could switch on or off. A default install of Unbound, for example, seems to /just work/.
Downside: if you have any kind of home network, running your own recursive DNS probably implies running your own DHCP, which isn't normally a consumer alternative (you could do it using settings on a domestic router, but not if it's crippled or locked-down). Also, DNS caching shouldn't be so effective (but I haven't noticed that effect).
Upside: all kinds of problems resulting from relying on DNS servers controlled by others disappear. You're not relying on them any more.
Downside: if you have any kind of home network, running your own recursive DNS probably implies running your own DHCP, which isn't normally a consumer alternative (you could do it using settings on a domestic router, but not if it's crippled or locked-down). Also, DNS caching shouldn't be so effective (but I haven't noticed that effect).
Upside: all kinds of problems resulting from relying on DNS servers controlled by others disappear. You're not relying on them any more.