I am specifically not talking about maintenance, EME, signals and those kind of technical branches of the armed forces which are in most ways directly support combat ops.AOC-in-C Maintenance Command, ACAS Engineering
Army:
Lots of Engineer Lieutenant Generals have been Army Commanders (Noble Thamburaj, S. Pattabhiraman, PS Bhagat, etc etc)
There is a post of Chief Signals Officer who is a Lt Gen, as well as the Comdt of the MCETE is a Lt Gen
DGEME who is a Lt Gen is an engineer, as is Commandant, MCEME
A Naval Architect is NOT an operations officer. He cannot be the Chief Engineer of a ship . He is by definition an R&D kind of officer, who usually works at designs and development and is more shipyard /design oriented than running the ship. In fact, a Naval Architect is NOT qualified to be a ship board engineer, that is always the preserve of Marine Engineers, both in the civilian and military world.
It is like saying an Aerospace Engg is going to do Aircraft Maintenance Engg. That is a separate certification and a different course altogether and so is the Engg officer that aircraft of yore carried to operate systems etc , esp in large civilian planes.
What I mean is that the Army and Navy dont have equivalent R&D kind of specialized cadre in the first place, and even if they did, there isn't a career path for them.
That is very different from saying that there are 10 Lt gen positions for people in the technical streams in the army (signals, engineers, maintenance, even as someone said doctor) or air force.