Short answer - NO.
The initial stepped climbs on SIDS are due to the interaction of having 5 (+) busy airports within such a confine.
The stepped climbs you are talking about (FL80-FL100 in this instance) and other similar levels are due to crossing traffic. Doesn't matter what speed you fly at - the crossing traffic will be there.
Some days you get lucky and miss any crossing traffic, others you interact with a lot of aircraft before leaving the LTMA and hence get lots of stepped climbs.
Although a jumpseat ride is agreeable - and a good idea for many reasons, the only real way to understand why climbs are stepped is to visit the centre in question and see it in action.
Crossing traffic is the problem, not aircraft on the same route flying different speeds!
At the very least, the people who come up with these half-baked theories should avail themselves of charts with the route structures drawn on them - I'm sure your local ANSP would be happy to provide them to you as a customer.