The purges had been bad in general because most of the victims did not commit any crimes against regime (which does not mean that most of the ‘heroes’ of the RCW did not deserve to be executed for the crimes they committed during that war but this is besides the point). So it makes sense to discuss only practical impact and on that issue I agree with you.Any adequate government will not tolerate an alternative power base in the army.
No. The reason for the lack of command staff is not repression. And the fact is that the number of the Red Army from 1500,000 people in 1937 increased to 5000000 people by June 22, 1941. And by July 1941 up to 10000000 people. And before that, from 600,000 people in 1932 and up to 1500,000 people by the beginning of 1937. The absence of repression will not help in any way. Moreover, I doubt the military genius of Tukhachevsky and other repressed officers.
Well, it can probably argued that an absence of the purge would make things somewhat better just because the old cadres at least knew the routine but an overall value of the military victims of the purge is a big question mark.
To start with, most of the senior commanders raised during the RCW and after that did not overburden themselves with a continued military education. Take, for example, Marshal Blucher. One of the top heroes of the RCW and quite loyal to Stalin who was even ready to overlook his drunkenness (“old horse knows the route; today he is drunk but tomorrow he’ll sober up”, etc.) but the 1st relatively modern military conflict on the Lake Hasan demonstrated that Marshal has no idea about the nechanized war and this was an end of him. Tukhachevsky, putting his personal issues with Stalin aside, was a capable person (but his encounter with the marginally “Western” Polish army was a disaster and since then he was obsessed with the revenge) but his ideas regarding mechanization of the Red Army were on a fantastic side numbers-wise (levels of the military production he demanded never were reached) and were not necessarily going in the right direction. Theory of a deep offensive, routinely attributed to him, was actually developed by Triandophilov well before the purges (to be fair, Tukhachevsky supported it bit went slightly overboard with its practical applicability) but remained mostly on paper (Kiev Maneuvers was seemingly mostly a showcase) and clumsy attempt to implement it in 1941 resulted in a loss of most of the Red Army’s armor. It seems that there were few successful implementations later during wwii.
Then goes military education. The military education became a part of the standard high education in 1926-27 so the graduates had been getting a lower officer rank and were considered officers of the reserve while having close to zero experience of a military service. Taking into an account that most of them had been called to service at the start of the war we have a generally incompetent body of the low rank officers.
The professional military academies and schools. Who were the instructors in the terms of their qualification if most of the officer corps (from which these instructors had been taken) was severely under-educated and had been very skeptical about the usefulness of the theoretical knowledge (much advertised Zhukov was openly expressing opinion that the graduates of the General Staff Academy are all idiots)?
A standard “spiel” is that there were numerous officers of the Russian imperial army who went to serve the Soviets and had been purged. This is, of course, correct but it is often an overlooked fact that by the 1917 a big percentage of the officers with a rank below colonel had been war-time promotions, often after the rudimentary war-time school. Brave and capable people but not necessarily with a good military education. Some of them after the RCW graduated from the RKKA Academy but was it enough?
Then, look at the performance. By the start of the war most of the army level commanders were from the same pool as the victims of purges and at least Pavlov was for a while overseeing development of the mechanization program. But as soon as the things had been getting wrong many of these commanders had been abandoning control of their troops and, at best, were trying to get out of encirclement on their own. Is there a valid reason that most of the purges commanders would perform much better?