There are also many other logistical hurdles that you must overcome to accomplish X. The problem is that often, I do not need to attend the meetings, nor do I need to overcome the logistical/political) hurdles to accomplish X, and more often than not these are impediments to accomplishing X.
It really varies from company to company, my point is, I want to get paid for the time, because I can never be certain how much I will have to waste in meetings and other un-related tasks before I can complete a given accomplishment, due to dependencies on others.
Add to all of that the litmus test of a completed "accomplishment" can be very subjective, e.g. something one person thinks is done, is not seen that way by someone else, and you don't get paid until everyone agrees it is done?
There's also the old scope creep monster, that rears it's ugly head. What you had to accomplish at the beginning of the project changed half way through and now you have do twice the work to complete the "accomplishment".
My time is the most valuable thing I have and the older I get the move valuable it becomes. I'm not going to roll the dice that whoever is writing the checks will have the same perception that something was accomplished as I do. I don't want to have to spend more time to "accomplish" something, just because someone "moved the goal-post".
On the other hand if you are a consultant and it's a vendor/customer relationship, then it's up to you as the vendor to define the "accomplishment" and build in a way that both vendor and customer can agree on when an "accomplishment" is finished. Scope creep is handled by additional statements of work, etc.
When there are contracts and potentially lawyers involved, paying for accomplishments is a little more tenable, in an employer employee relationship, where as the employee if you don't like it you can find another job, not so much.
Imagine if every time you got paid you had to have a meeting with your manager to determine exactly what you had accomplished, with the manager making the final decision on whether it was done or not? Suppose they decide that program you wrote needs more testing to be "accomplished", or an extra feature that was not originally scoped needs to be added and until such time, they aren't going to pay you? That sounds like the stuff of nightmares to me.