There's metcon, and then there's metcon.
Chippers and long, slow distance are one thing; short circuits with moderate loads are quite another. Since all I care about right now is improving my total (and, of course, big guns), I do neither.
But before I went all the way over to oly lifting, when I first started it after doing the WOD for a while without strength gains, I took the middle way of restricting my metcon to low-rep, medium-weight, rounds-for-time circuits. Really low reps, e.g., once a week a did this after an oly workout:
Max rounds in 10 minutes of:
-5+5 2 pood snatch.
-5 light back squat (70%)
-5 weighted chins
Then once a week after an oly practice, I did Grace, which of course was also under 10 minutes. After a couple months of this, with a few 100m-200m sprints easy thrown in before workouts, and I could still run a 5:00 flat mile.
The lesson, IMO, is that you can to some extent--to some extent-- minimize endurance adaptation in muscles and maintain or even improve anaerobic/ short-duration aerobic conditioning while concurrently increasing strength and power--so long as you stick to low reps in circuits.