You are simply wrong.
Elefant was the most successful mass produced TD in kill ratio with around 10:1 score.
the elefant/Ferdinand had been the product of a "mistake" (it was never really planned to exist in the first place), and had been made with extreme flaws that were never fixed. The vast majority of kills have been made during the battle of Kursk, taking down around between 200 and 300 tanks (vast majority being the T-34/76), and essentially all of the losses were due to mines and mechanical breakdowns (around 10-15 elefants damaged). having a massive anti tank gun and extreme frontal armor (200mm) basically ensured that it would hit first, and no hits could really harm it
but, "most successful mass produced TD" is a completely moronic term used in the context, because the elefant was not successful at all beyond in paper. it has theoretically gotten up to 320 tank kills, but this number "could" be inflated. If it wasn't, the tank had been riddled with problems that hindered it extremely (it would catch fire when driving up small slopes, endless transmission and engine problems, etc). It was NOT mass produced/limited numbers (all production numbers are converted from already existing tank hulls), it's relevance has gone down significantly after the battle of kursk (it was used to the end of the war, but it wasn't an effective TD), and the list goes on
in a vacuum (and in the game), the elefant is a very good vehicle. But in reality, it was probably more trouble than it was worth. "The most successful" axis tank destroyer, or tank in general, was more the stug, because it's war impact and effectiveness (for its cost) was significantly higher than most of these big "terror" machines
The Elephant may not be the most mass-produced tank, but the threat of the new self-propelled gun and the long-barreled 88mm cannon was taken seriously by the Soviet leadership. So the development of new tanks began that could be protected from the Pak 43/Kw.K. 43 this way the T-44 and IS-3 appeared.
The USSR also lost a promising light tank during the war because the Main Armored Directorate of the Ministry of Defense demanded 90-mm frontal armor from the new light tank like the T-44, which protects against Pak 43/Kw.K. 43
And all this only from the appearance of the Elephant at the front.
well to be fair, the soviets have faced the 88mm AT gun in larger quantities both before and after the elefant, so this was a completely sensible decision.
unfortunately neither of the tanks would be used before ww2 ended. Fortunately they made 3000 IS-2s, whose protection was at least partly resistant, and whose guns blew apart even jagdtigers