Early season PvP is much less impactful to raid and m+. The grind also lasts only a couple of days to get a socketed piece of 610 ilvl, and you don’t even need to win to get said rewards.
The flip side is not true as m+ and raid directly affect each other thru a big chunk of the tier.
Even if you overlook the gear drops from m+, there is still the crest currency that drops; and as I previously stated, you are not capping them from raid unless you’re clearing most of the raid.