AKA most dogs are dingoes. The long term pariah morphotype is basically when dogs (especially most stray dogs and most dogs in general) look more like their wild counterparts like wolves and foxes and to some extent behave like them too. Especially if they’re not so socialised to humans even if they’re owned. (One of my dogs kills frogs a lot.) Not to mention that dingoes are believed to be closely genetically related to many stray dogs.
Parsimoniously speaking, most dingoes (as well as certain breeds like Siberian Huskies though it depends on the individual dog itself) can’t process starch any further. My own dogs can’t take starch either. (That’s from being fed on rice a lot.) In fact many of them have died and only a surviving few have certain ailments like glaucoma, stunted growth and being overweight. It could be due to other factors.
Though I won’t be surprised if somebody made a study assuming that most dogs have more in common with dingoes (both behaviourally and biologically) than they do with most breed dogs and there’s an earlier study suggesting that most breed dogs come from an earlier dog population. If dingoes are assumed to be one of the more basal dog populations, it should make sense that most non-breed dogs would skew closer to dingoes.
(Interbreeding with wolves also helps in increasing genetic and behavioural wolfishness especially wherever wolves still exist.)