@masstika: In the perfume industry, there are two types of vendors: there are vendors of perfumes – be they colognes, eau de toilettes, solid perfumes, botanical perfumes, natural perfumes, 'mukhallats' – and there are vendors of perfumery ingredients – essential oils, concretes, absolutes, floral waters, CO2 extracts, etc. The first never claim to offer the wares of the second group, and seldom does the second group attempt to purvey the branded merchandise of the first.
The first group offers a box, a container, and a fashion statement. The second group offers an artisanal, crafted, natural substance which may or may not be employed in the production of the wares of the first group. When looking for pure oud oil, you are as likely to find it on offer with brands or 'big houses' like Ajmal and ASAQ as you are to find pure deer musk on offer with Dior, Frederic Malle, Serge Lutens, or even Mandy Aftel.
You have the 'oudh', or the 'aoud', of the perfume houses which is a branded, generic Arabian (or Middle Eastern) fashion statement that is slowly gaining popularity in the West – and you have the artisanal oud oil, or pure agarwood essential oil of Ensar Oud, which is the natural raw material to which this scent category owes its original archetype.
Ajmal, ASAQ, Rasasi, Arabian Oud, Al Haramain, Oudh Al Anfar, King of Gaharu et al do not advertise organic, authentic, natural agarwood essential oil. Rather, they advertise the fashion statement of 'Arabic oudh', which is as general a scent category as it can get – not a scientifically defined natural raw material.
A good simile for how much oud oil is present in a bottle you receive from any of the 'big houses' is afforded by the other 98% of the perfume industry and its big houses.
Just as realistically as you can expect to find proper deer musk in: Frederic Malle's Musc Ravageur, Mona Di Orio's Les Nombres d'Ore Musc, Muschio Nobile's 1942, Keiko Mecheri's Musc, Creed's Cyprus Musc, Mazzolari's Musk, Micallef's Royal Muska, Montale's Aoud Musk or White Musk or Musk to Musk; Nasomatto's Silver Musk, Serge Lutens' Clair de Musc, Coty's Wild Musk, Dior's Homme Intense... and as much sandalwood as you might find in: Creed's Original Santal, Le Labo's Santal 33, Bois' Sandalo, or Serge Lutens' Santal de Mysore – that's how much agarwood essential oil you can realistically expect to find in any of the 'oudhs' or 'ouds' or 'aouds' from any of the Arabian or other 'houses', big or small.
For Ensar Oud, agarwood oil is not only a very specific type of essential oil which is extracted from a certain species of tree possessing a necessary degree of resination triggered by certain traumas – it is a painstakingly defined grade of that essential oil.
For John Doe, 'oud' could be any ratio of that oil in combination with any other oil, be it of natural or synthetic origin. For yet a third, it might be any combination of dioctyl phthalate (DOP) in conjunction with other chemicals. And for the 'big houses', it is a scent category.
Just as musk is for the 'big houses' of French perfumery, so is 'oud' for the big Arabian houses – a type of smell – regardless of what substance is used to give off or emit that smell. Nowhere do they advertise that they are selling 'agarwood essential oil'. Rather, just as Serge Lutens sells Muscs Koublai Khan, containing zero deer musk, so can – and does – Rasasi sell Attar Al Oudh, containing zero agarwood oil.
The 'big houses' can never offer artisanal oud oil on a large scale for the same reason Serge Lutens cannot offer wild-harvested deer musk on a large scale, and the same reason that instead of pure santalum album from the state of Mysore, Creed offers Santal Imperial, Original Santal, Bois de Santal, etc.