Ok, I really should have said 99.9% sure. There is always the small chance Funcom really does want one person to let hundreds/thousands of people into MC that have never killed Sheng-Emperor.
- 60 sec Louhi kill
This is iffy. Funcom didn't expect players to be able to manage to kill Louhi that fast. But, when nearly geared out/good players poured on the dps, they managed to kill the boss before the script could continue on to the next stage. Players aren't really abusing a mechanic, they are simply completing the encounter faster than expected, thereby not haveing to deal with the full encounter mechanics. You could say it was unintended, and Funcom did alter the fight to make that less possible.
- kill Athyr Bast tank&spank style
This has honestly always appeared to be bypassing the mechanics of the fight to me. I have never seen the fight done any other way and have only read about the intended mechanic.
- kill Kyllikki before she runs off to summon the adds
Same thoughts as 60 sec Louhi kill. If you can manage to down her before the raid script can continue its normal operation, that simply means you are a really strong raid force.
- kill Vistrix before it can do the stun spell
Same as 60 sec Louhi kill or Kyllikki.
- shard farming using the tables
I'm not sure what you mean by shard farming using the tables. I admit I haven't shard farmed a ton. Is this something like standing on tables where mobs can't attack you so you can kill them easily while solo?
A lot of this comes down to encounter design. An encounter may be made with a specific idea in mind about how to complete it, but that doesn't mean all other methods are exploits. Game developers expect players to find new/creative ways of doing things. It is just when they take things too far and abuse an unintended mechanic that things start to be classified as exploits.