and neither have a chance of beating RB.What are you on about, Mclaren is ahead of Merc and has been for some time now...
but I cant think of a single case (after looking thought the list of constructors champions) where a customer team beat the supplier team to win the championship.
from a business point of view if your engine is not the best you want to be sure to occupy as many as the non winning spots as possible that way more people want to buy the engine right? so for Merc it pays to have Aston, Mclaren themselves and even Williams finish as high up the order as possible and the more of those that finish ahead of ferrari and ferrari powered teams the better for them. this is also true for Ferrari.
on the flip side when Merc is winning races you want the other merc powered cars at the front without being ahead of merc.
so if Mclaren finish ahead of Merc this year and next year its fine, but if Mclaren is actually fighting redbull and Merc is not then there is a problem and it will look like merc is not a good engine supplier if a customer team can win the championship when they cant....