The SA-11 'Buk' TELAR (9A310M1) was indeed designed to be used as part of a broader system including C&C, dedicated launchers, and the 9S18M1 radar. It certainly requires trained personnel to operate.

With that said, the Buk was also designed to surpass its predecessor('Kub') by incorporating a fire control radar into each launcher (TELAR vs TEL), so that it could operate with some autonomy. The original idea was to allow the whole SAM network to track multiple targets independent of the 9S18M1 radar, which would focus on detection and delegation.

This capability also enables an autonomous TELAR unit (as the various images and videos are showing) to target an aircraft at a range of 3-32km, much as people are hypothesizing happened to MH17. It is plausible, although far from certain.

http://fas.org/man/dod-101/sys/missile/row/sa-11.htm

That's why I called them marginally-competent instead of drunk wannabes.

I'm not 100% solid on this, but I have read that they were using just the missile truck without the supporting air-search radar. The missile trucks apparently have fire-control radar and can attack and aircraft by themselves. It seems plausible that they were given or stole just part of the system - the missile truck - and maybe got some manuals or some hasty training from Russian military or something. So they know enough to fire the missiles at a target, but don't have the hardware or training to operate a proper air-search radar and identify their targets carefully first.

Which is why I think it's mostly likely that it was them. Say what you will about the Russian and Ukrainian militaries, I doubt they'd accidentally shoot down a civilian airliner.

The rebels had already shot down a number of Ukrainian military aircraft before this happened, so it looks like they can operate the system.

Landing transport planes, su-27's on a bomb run, helicopters. Easy targets for simple shoulder fired missiles ,that's what Afghani sheeperds were doing to soviet and american armies - just a dumb Stinger missile

An Antonov AN-26 was shot down at 21,000ft on July 14. Assuming that the Ukrainians don't shoot down their own military aircraft, it was either shot down by the rebels or, possibly, the Russians. The rebels took credit and there is no real evidence that the Russians did it, AFAIK. Also, the twitter comments by the rebels immediately after MH17 crashed, and the conversation between rebel commanders released by the Ukrainians, speak against direct Russian involvement. (And on top of that, although militaries certainly do make big mistakes from time to time, it is clearly more likely that the poorly trained rebels would have made a huge fuck up like this than that the Russian military would have done so.)