Closer to the generally accepted, but it is good practice to substitute "serpent" for "dragon". Next to "Father Sky", the existence of a serpent-slaying club-wielding archaetypical warrior storm deity, possibly with a human "first warrior" or "hero" counterpart, is probably the single most accepted feature of proto-indo-European myth. Not only is it basically universally attested and often a reduplicated motif, it seems to have been so compelling a narrative it seeped into other mythos, like that of the Near East and Japan.

If there's a controversy around it, that more surrounds attempts to infer facts abour PIE society and what these stories represented (e.g. ideals of masculinity) to the PIE:s. Reconstructions like this are ultimately always a bit artificial - just like the reconstructed PIE language is unlikely to correspond exactly to any one dialect, a reconstructed pantheon is unlikely to have corresponded to any one belief system. Even within the same society, the same stories will be told and retold for different purposes, to different audiences. Indeed, whereas in Near Eastern myth the serpent represents the primal ocean, in Indic variants it is responsible for the drought of freshwater rivers!

The best popular introduction to PIE society is The Horse, The Wheel & Language.