I have to believe the landlord is either unaware or does not fully understand what is in the lease.
The agent certainly does not understand the legal risk to him/her and the firm in presenting such a lease.
Example: I do not rent to smokers. Not open for discussion. If you smoke in my property I can evict you. At a minimum you will pay for a good cleaning of the unit out of your security deposit etc
No. At minimum, the tenant will get several months free rent once you start an eviction for smoking, and the tenant stops paying rent. You may very well get a judgement for the cleaning allowing part of the deposit to be kept for that (as opposed to applying it to unpaid rent - in any case you keep the entire deposit while losing several months rent).
Sure, you will get a judgement for the uncollected rent, but good luck collecting.
Unless you have some free legal resources it will cost you and the landlord a lot of money and in the end not much will change.
But, if you do have free resources, you are in the driver's seat.
If you win, the policy will change, the landlord will not have a choice, and you will have another cause of action if there is a retaliatory eviction or non-renewal of lease. I don't call that "not much". If the landlord non-renews and changes the use of the building, you don't have much of a case - but if the landlord terminates your lease, and rents to another party, you would have a valid case for damages due to retaliatory eviction, termination or non-renewal.
Also in my specific case you will be on the street regardless because all of my leases, that you would have signed, have a clause that allows me to terminate the lease for no reason with 90 days notice.
A clause that will be held to be void if the court determines that said termination is retaliation for a legal action to enforce a legal right.
I agree with the strategy of giving the landlord a chance to make it right before taking any action.
But, landlords only have power when dealing with upstanding citizens who believe in honoring their word; paying their bills; and not screwing people over. If you get a tenant who does not subscribe to the value of the working, honest, taxpayer most of the power you think you have as a landlord vanishes.
Two classic works in this area are "The care and feeding of tenants" and "Tenants revenge", buth written by a scummy Rochester, NY landlord.