I understand what you are saying 30W, and the extract you posted was added after a review. It was decided to thin out the MATS Part 1 (also many other items have disappeared) and make it more generic and high level. By adding the specific content back in will only continue confusion, as every scenario just cannot be written down otherwise the Part 1 will be the size of the whole set of the Britannia Encyclopedia.
Are you insinuating that by being given a vector, it will technically amend the route so any level restrictions need reiterating? That is how I am understanding the issue here and I disagree. If I have given a level restriction using the example originally quoted to be FL180 level KUMIL, then I give a vector or two (3,4,5....) and then resume the aircraft own navigation back to KUMIL in plenty of time, why would the aircraft not achieve the restriction, or what have I done to cancel the restriction? How about on first call I say descend FL200, expect FL180 by KUMIL, then issue a vector?
The MATS Part 1 as far as ATCOs are concerned covers what is needed. If a new routing or new level is issued, any required restriction needs repeating. A vector does not constitute as either of these.