If Details addon was trustworthy then the parsing of WoWCombatLog.txt would perfectly match the #s. It is far from matching perfectly. If Details was accurate, then I would be the top DPS on one-third+ of bosses, but Details is inaccurate because of its client basis. Parsing only works with WoWCombatLog.txt because its #s come from the server.
You, Sir, are the misinformer.
The way Details addon could and should work, to be accurate, would be to parse WoWCombatLog.txt in real time. This has not been done in the decade since it was first coded, though, so don’t expect it.