Question about Arms Race

Dear everyone,

In the Arras Arms Race mode, many new tanks are introduced, giving players more freedom over their preferred playstyle, but a few of the classic tanks have been removed as well, for example the desmos. Removing certain tanks also prevents upgrading into a few tanks. For example, the removal of the desmos prevents upgrading into helices, triplexes and quadruplexes. Why did the developer remove a few of the 120 classic tanks in Arms Race?