Leaning one way or the other is a colloquial expression of opinion. In my case, it's opinion from having read a number of studies, not from doing research.
I don't have the CV required to get employment in a lab or to get funding. I'm purely an amateur, took up studying molecular biology in my retirement (from software development, if that matters). I do have a background in statistical analysis, but I've only used that in a Baysean sense; the more 'power' (ability to generalize results) and the more statistical significance the more something 'pushes' me off my prior assumptions. Yes, Bayes was involved with the Church - but his analysis has nothing to do with religion. it gets used in software a good bit, particularly if results are murky (e.g. 'is this piece of email spam or not?')
I picked molecular biology mostly because I never had any schooling in it, so it's hard - particularly the necessary organic chemistry, which I have been picking up as I go. I'm sure I've gotten some of it wrong...
Oh, and yes plants absolutely have cell walls - but Herculano-Houzel didn't work with them (and why would she - she was looking at the power laws between CNS nerve cell size and overall body mass between different species). Without getting into the electro-chemical communication going on between all eucaryotic cells (so including plants) they don't seem to have nervous systems.