the widely held view in Europe is exactly what I said.
If so, that's because that's what they've been told by their media and possibly "aviation experts".
Now the BUK, as has been discussed here many times, had its origins in Soviet Union defence systems, and when the Soviet Union split into its constituent republics, both Ukraine and Russia ended up with BUKs. There's been a long debate about whether the missile battery was brought across the border by Russian forces, or was captured from Ukrainian government forces by what you call irregular civilians.
There's no debate about that, unless one is dealing with a Russian propagandist. There are photos of the BUK which have been widely published in the public domain which show the transporter coming and going from and to the Russian side.
You speak in strong tones: "I don't think anyone has ever alleged......." "There's been a long debate........" yet you spin the actual facts. What part of Europe are you from? I'm west coast American BTW.
And you continue to spout the Russian message (it's all so confusing, how can anyone know?).
I doubt if we'll ever know if they were renegade Ukrainians or Russians pretending to be renegade Ukrainians, since both groups were Russian speakers. What is crucial is who made the mis-identification of the scheduled passenger plane (which had clearance from Russian ATC and Ukrainian ATC to be where it was) with a military aircraft, and told the BUK operators to fire at it.
Mis-identification? Are you sure about that? Maybe they just wanted the next one to come along.