Three separate things get folded into the word smudging, and they need pulling apart before anything sensible can be said about it.
Burning plants for smoke
Universal, or near enough. Frankincense in churches, agarwood in Japanese temples, mugwort in moxibustion, benzoin in Southeast Asia, juniper across northern Eurasia. Nobody owns this and no tradition claims to. Anyone can burn a herb.
Specific ceremonies of specific nations
Also real, and a different matter. Purification with smoke occurs in the practice of a great many Indigenous nations of North America, and it is not one practice. The plants differ, the words differ, the occasions differ, who may do it differs, and in several traditions the ceremony it belongs to is closed. Collapsing that into a single generic act called smudging, performed by anybody, over anything, is the first error, and it is an error about facts before it is an error about respect.
The legal history matters here and is recent. Ceremonies of this kind were suppressed in the United States for decades and were not clearly protected until the American Indian Religious Freedom Act of 1978, with the position sharpened again by legislation in the 1990s. People are alive who were punished for practices now sold at checkout counters. That is the specific grievance, and it explains a sharpness of tone that otherwise looks disproportionate.
The plant itself
White sage is Salvia apiana, a Californian shrub, and it is not the culinary sage of a kitchen, Salvia officinalis. Its ceremonial use is particular to Indigenous Californian and Southwestern nations. It reached the general market through the twentieth-century commercial spiritual trade, and demand now vastly exceeds anything traditional use required.
The consequence is documented rather than speculative. Wild stands in southern California are under harvesting pressure, poaching from public and tribal land has been prosecuted, and the plant's conservation status is monitored. Native people who need it for ceremony are competing for it with a wellness market. That is the point at which a question of taste becomes a question of access.
There is no tradition that owns smoke. There are traditions that own their own ceremonies, and there is a plant that is being taken faster than it grows. Those two sentences are the whole of it.