Detrimental? On a one-off ride? No. Repeatedly, depends.
Effective? Depends.
The entire point of structured training (I'm not sure what "tiered" is) is progressive overload and recovery, in which the training stimulus increases such that your fitness can also increase when adequate recovery is allowed.
If you're planning an easy z2 ride, and then a workout, and you uncork a bunch of efforts in your easy z2 ride to such an extent that you can't do your next workout, then you're shooting yourself in the foot a bit and doing this over the long term is going to hold back potential progress.
If none of it really mattes and you just want to have fun, then just do what you enjoy.
Also, sprinting is a 5-20 second effort. 2-3 minute efforts are an altogether different thing, and more difficult to recover from when done on a continual basis. Whereas a z2 ride with 3-4 5-10 sec sprints isn't likely to affect you much differently, a z2 ride with a number of 2-3 min efforts is essentially a fartlek workout. And your aerobic system is always contributing to energy production, so any ride you're doing is training your aerobic system.
And finally, I've never ascribed to average hr or average power telling the whole story of the training ride unless it was deliberately steady. Average hr/power doesn't mean anything if you're continually doing efforts above and recovery below whatever zone you're shooting for.
Doubly finally, if you're doing structured training, after a couple of weeks your workouts will be such that you might just relish the thought of a z2 ride with zero accelerations. Doing proper workouts can leave you hurting and really zap that "fun" part of punching it up every hill you come to.