Your doubts are well-founded
S-300’s are launched in pairs not 3’s
Russia is regularly destroying Ukrainian S-300 systems
being provided by 3d countries and has no shortage
of accurate missiles used to take out weapons depot, fuel,
troop concentrations and recently, high level military planners
not to mention if they were using them as StA, then all of them missed!
proof being no footage of hits or as to their inaccuracy, which