Its not how it was IRL but you can adjust distance manually. There is manual range adjustment its called something like 'Sight Control'.

If there were only 4-6 tank models like in RO then yes but in WT there are much more different vehicles which had different sights. They said its too complex as there are just too many vehicles to cover. Most optics are used on more than one tank to begin with. For those tanks where our Devs can't get information on the optics used they could still use the optic we have right now with manual range adjustment. Getting to recreate the historical optics should be the easiest part of implementing a tank for WT. Ez Waffen SS Uniform EZ Armd Inf Uniforms German Winter Faces CMBN New MG34/MG42 LMG Animations By Frenchy56 MOS Remove Some German Helmets MOD for CM WW2. Even Forgotten Hope, a BF 1942 mod from a 15 year old game had working Zeiss Optic gun sights in their tanks implemented in a game, that didn't made use of manual range adjustment before.

Ro was in it's first instance an ego shooter focusing on infantry battles, who's tank parts weren't really fleshed out properly. Still the adjustment of gun sights worked perfectly. Yet I still don't see what's 'too complex' about it. World War 2 was a combined arms effort, with land, sea, and air forces offering equally invaluable efforts, and War Thunder truly captures that.

War thunder infantry mod