I would say yes. Eventually someone is going to bump into the bike or it will just slip. Garage floor is likely hard so some cosmetic or even mechanical damage could occur.

Here is what I use: https://www.amazon.com/gp/product/B00CW911SM

Being that this or any stand is going to be ~$50 (or less) and should last a lifetime, I'd say 100% worth it.

Congrats! I received my ALR5 about two weeks ago and I love it. I picked up this floor stand off Amazon and have been pretty happy with it: BIKEHAND Bicycle Floor Type... https://www.amazon.com/dp/B00CW911SM?ref=ppx_pop_mob_ap_share

This one here

BIKEHAND Bicycle Floor Type Parking Rack Stand - for Mountain and Road Bike Indoor Outdoor Nook Garage Storage https://www.amazon.com/dp/B00CW911SM/ref=cm_sw_r_cp_api_glt_i_R1MBE08X5XCV79M21DS2?_encoding=UTF8&psc=1