Not really, penetration of SU-76 for example is incorrect in Cruz doc as it was nerfed less then 2 years ago.
I don't recall this nerf at all, please link to the patch.
While there are specific situations which favor the allied light vehicles(such as the stuart ambushing the puma with stun shots) the puma is advantaged over all but the su76. This is due to the range, and I have to echo what felix implied: if 10 range is insignificant or marginally useful to you, this is just an indicator of lack of player skill.
(A 3-5 frame timing difference on a move in a fighting game might seem trivial to some, but in the hands of an expert it makes all the difference)
The Su76 has superior penetration and range over the puma which means better scaling, the light artillery barrage gives it arguable better utility vs infantry and weapon teams and falls into a natural tech progression. In the dedicated anti vehicle/tank role the Su76 is definitely superior, but its not built often.
The su76 us often skipped for two reasons. One is that while it is at a timing and cost appropriate to counter enemy shock light vehicles such as a luchs, the reality is that the T70 is so powerful that it's usually taken over the su76 and can counter them on it's own as well as being a powerful anti infantry platform. Then due to the delay between the t70 and another vehicle, Soviets substitute Infantry based AT such as penals or guards or zis to supplement the t70 in order to cheap out and save for tech.
The second reason is that the Su85 serves a very similar purpose as the Su76 while scaling better and being more potent but less of a glass canon and thus easier to keep alive. If you are going to need a long range TD with good penetration, better to just wait for an '85.
The other two have their own niches as well and are important to their respective factions in different ways. The AEC being UKF only medium vehicle but with the ability to provide support via treadshot against heavier vehicles, and the stuart being a strong counter to axis light vehicles (excluding the puma) which once clear give the stuart several minutes of uncontested time on the map.