We lost our $2M business after being back stabbed by our partner and fighting lawsuits.

If you fail to follow the rules, you may open your personal assets to a lawsuit.

I have read and heard that putting each property on a different LLC will protect you from any lawsuit (in case there is one) and also help you reduce taxes. 

The landlord then has a single, powerful remedy: a court action to evict you and recover the unpaid rent (called an "unlawful detainer [eviction] lawsuit" [see The Eviction Process]).

Keep in mind, with the LLC or insurance policy you are trying to protect your personal assets and in the US (for the most part) your personal residence and qualified retirement accounts are protected and generally considered untouchable in a lawsuit. 

If you can't negotiate it with him then you have to file a lawsuit.

I vision your jeep upside down at the bottom of a cliff with a few dead bodies in it and your receiving a multi-million lawsuit that states you did not provide proper training that explained how to reduce speed and how to properly apply the brakes. 

If the wholesaler obtains a license, then wholesaling may subject him to a lawsuit by the seller for having violated his fiduciary obligations as a license holder.

Another reason that comes to mind is lawsuits/bankruptcy/financial issues.

Additionally, sheltering your capital from law suits, foreclosure, etc. is possible via leverage.