I think your installer was being lazy. The X5M is only rear air ride, but regardless of whether or not you have coil springs or air springs you have a separated damper in the rear. In the front you have a combined spring/strut but in the rear it's a spring by itself and then a damper(strut) by itself. On both the front and the rear the bump stop prevents complete compression of the damper(aka strut). The DINAN kit has front coil springs and rear links to adjust the air spring height. It's easy to install the front bump stops when installing the spring because it all comes apart, but the rear you only need a 10mm wrench to install the links. To install the rear bump stops you have to take apart the whole trunk/storage area to unbolt the dampers, unbolt from the lower control arm underneath, pull them out from the bottom, and install the new bump stops. The installer probably didn't want to go through the hassle and called it a day.
Here is the rear Damper with the bump stop highlighted:
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2020 G01 X3 30e
CURRENT M Sport Package
2019 Ford Raptor SuperCrew
CURRENT 802A, KN Drop-in, RB Flaps, Husky Well Liners
2012 E70 X5M
SOLD Stg 1+ Turbos, DPs, Velos Stg 2+, JB4, Race Cats, Bavauto Coils
2003 E46 M3
SOLD aFe CAI, AP Axleback, SSK, H&R Springs, TMS CMBR Arms, PF RTABs