I think the ARP unit is doing a decent marketing job, they sell their product based on the fear that your unit will be damaged if you don't use their product when parked improperly.
I also wonder how many fridges are actually damaged by running out of level, and how much out of level and how long they stayed out of level. The ARP unit obviously operates as described and can prevent the kind of issues they say can occur. But is this a serious, oft occurring problem, or is it only an occasional problem that doesn't warrant the expenditure for the majority of fridge owners?