That is an interesting paper, as is the co-morbidity of ADHD with epilepsy that they cite. It's also hopeful for some people suffering from ADHD because it is suggestive of the possibility of a more complete treatment for some.

However there's a general understanding of ADHD (and related disorders such as ASD) as a spectrum of conditions with multiple contributing factors. Depending on the person ADHD will manifest with more or less hyperactivity, distractability, working memory issues, and lacking emotional regulation (among other things). Different causes combine to give a somewhat amorphous disorder with a range of common symptoms.

So adding a new treatment with fewer downsides (because stimulants can have a few) is great, especially as it might treat aspects of the disorder that aren't treated by stimulants. But this doesn't mean stimulants won't still be relevant in the future.

There's there's also plenty of research showing specific dopamine receptor dysregulations as contributing to ADHD. See for example https://www.researchgate.net/publication/364120700_Dopamine_...

So unless the research also shows that this is caused by pyridoxine metabolism problems, these hypotheses can both hold at the same time.

Picking some paper that talks about different causes doesn't mean other causes aren't still relevant. It will probably be decades before we can definitively rule out contributing factors.

PS It's generalizations like yours that are very stigmatizing towards stimulant use. We already know many people benefit from them enormously and significant numbers are not getting or taking them due to stigma.