The law permits property owners to put in deeds to buyers reasonable restrictions on the use of the real state being transferred. It might be looked upon as zoning on a very personal basis.
For example, a home in a commercially zoned area may have a restriction against use for any commercial purpose. This may be OK for the first buyer who plans to live in the house, but a lending institution may refuse to lend money on it because commercial use may be the only reason for a new purchaser to buy it. They prefer to play it safe and give funds for less questionable and risky situations.
From the point of view of the buyer, it is preferable that the agreement enumerate any and all restrictions. The point is this: if there are restrictions, bring them out in the open and get the advice of your REALTOR and attorney before going any further. It is for your own protection.