The idea of creating a heavily armored dedicated anti-infantry vehicle was not exclusive to the Soviet Union but it was the Soviet industry that started working on it intensively as early as in mid-80’s. The experience if Afghanistan and Chechnya taught the Soviets a painful, yet valuable lesson – even heavily armored vehicles armed with cannons were vulnerable to infantry in urban environment. The massive spread of and major improvements in infantry anti-tank weapons (mostly based on HEAT principle) further increased this thread to the point where for a certain time – especially in the west – it was thought that the tank would eventually become obsolete the way airships and armored trains did many decades before. Others however were actively looking for ways to tip the balance of scales in armored vehicle’s favor and one such idea was to create a heavily armored vehicle with anti-infantry armament to accompany the “classic” tanks.
Protecting your armored vehicles from enemy infantry required certain vehicle “features” not available to regular tanks. First and foremost, excellent gun elevation was required in order to deal with targets above you in hilly or urban environment. This was one of the first things learned by the Soviet troops in Afghanistan – enemy infantry would often be hiding on hilltops where the standard BMP-1 vehicles could not fire, since their elevation was insufficient and Soviet troops were forced to utilize anti-aircraft vehicles (which were well armed but very poorly armored, sometimes vulnerable even to small arms fire) as ground support. This issue was only mitigated by the arrival of the BMP-2.
Second very important requirement was to make the vehicle resistant to infantry weapons, specifically to HEAT launchers such as the famous RPG series. This called not only for thick armor (ideally composite) but also for the massive use of ERA, covering vulnerable parts of the vehicle – in Afghanistan however, such a technology was not available en masse.