The simplest explanation is common insertion points.
How would that explain the tree-like pattern? Are you claiming that these "insertion points" already mimic the phylogeny of the primates?
Also, it's not the simplest explanation. It is simpler to have one insertion event rather than half a dozen.
The phenomenon under discussion is the fact that, say, people, chimps, gorillas, and orangutans all have ERVs, some of which are unique to each species. However, if one is found in two species, then it will be found in others according to the tree-like pattern: if in gorilla and orangutan, then also in people and chimpanzee. If in gorilla and chimp, but not orangutan, then also in people, and not in gibbons. Etc Etc.
The 'tree-like' pattern has no organisms at the branches.
Can't you see that? It's a mental construct.
Just because there may be more than one insertion event in a preferred site doesn't make it simpler to have a single event followed by an impossible string of future events.
That's foolishness.