It isn't even the basics of the synthesis chain that are difficult. Most (small molecule) stuff a lab chemist could whip up a batch of given a bit of time and reasonable access to precursors.

But this is exactly like saying "Reddit is just a few SQL queries, a reasonable programmer could whip up their own version in a weekend." Just like there is only one reddit/StackOverflow/Facebook even though plenty of people have the same basic idea, even knowing the chemical formula doesn't help that much. The trick is in the execution: generating reliable quantities of reliable strength and without any contaminants.

There is a whole field, process engineers, devoted to this quite difficult problem.