I think the grouping would look more logical if it were made on the way the trees set fruit: stone fruit trees (plum, apricot) are the early bloomers, while the trees with fruits that contain seeds (apple and pear) are the late bloomers.
One thing important when pruning is that different species form their flower buds the previous year, while others form them the same year as flowering.
Apple trees and pear trees develop mixed buds on the top of each branch with the rest of the buds on the branches being vegetative. The mixed buds are formed on new growth, therefore, if not pruned every year, these trees will produce the fruits farther away and they will be harder to harvest. Pruning is done earlier in the year because the tree should be dormant, otherwise we risk pruning the branches that start to develop mixed buds. In this case, pruning can not be avoided during the period when the fungus Chondrostereum purpureum has its infectious spores active (from september to may). Of course we can prune them after they get out of dormancy, when the buds form, as long as we don't cut all the newly formed buds.
On the other hand, stone fruits form their reproductive buds later in the year, after the current harvest, and that's why they flower in early spring next year. If we were to prune them while dormant, we would cut the branches that had already formed their reproductive buds the previous year. Pruning after the harvest ensures both the formation of new buds and avoidance of the Chondrostereum purpureum active spores period. Pruning plums, cherries and peaches.
To summarize, stone fruit trees, which are early bloomers, need to be pruned later to avoid cutting the reproductive buds already formed the previous year, while the seed containing fruit trees, which are late bloomers, need to be pruned when dormant before the new mixed buds are formed.
Update: I have added links to RHS, a reliable source.