Historically the Soviet air Forces did not have to project power, or keep fighters aloft in Indian country for prolonged periods, and have always operated very differently from the USAF. As point defense aircraft expecting hoards of escorted (or not) US Bombers, their aircraft designs were generally based on defensive doctrine. Interceptors vs. escort fighters. That said the Soviets have been air refueling as long as we have, and with the same equipment, their first tanker being a modified Tu-4.
Selling their weapons now requires them to add the ability for the purchaser to “project power” across borders and oceans. They are doing so. I would not say they are 70 years behind. The KC-46 has its own issues, and drags a hose just like the IL-78.
..I wouldn’t say we are too far ahead.
https://en.m.wikipedia.org/wiki/Boeing_KC-46_PegasusOh! The MiG-21 was the best fighter of her generation, with almost 11,500 built, and still lethal today. An amazing design. And all fighters have short legs when the fight is on......