Critiquing Rent-To-Own (Ijarah Muntahiya Bittamleek) and Diminishing Partnerships (Musharakah Mutanaqisa)

Unfortunately most Muslim “scholars” are more theory-oriented than they are pragmatic. So let’s look at the theoretical argument for this product:
Is renting allowed in Islam? Yes.
Is a promise to purchase allowed in Islam? Yes.
Is purchasing through installments allowed in Islam? Yes.
From the aforementioned, nothing in the “Ijarah Muntahia Bittamleek” contract is forbidden and therefore the entirety of the contract is permissible.
And using the same line of logic,one can argue:
Is eating grapes allowed in Islam? Yes.
Is eating fermented foods allowed in Islam? Yes.
Therefore eating fermented grapes is permissible and Muslims can now drink wine.