"has pretty much achieved that already.."
No. A sample size of 18 (when looking at any population based study, regarding pretty much anything, let alone a highly invasive drug therapy) is not large enough, nor long term enough, to conclusively prove anything with certainty. There's a reason that phase II and then phase III grow proportionally much, much larger and enormously more expensive and include placebo and blinding, etc.
Then their is follow-on, follow-up safety studies and tracking, etc.
Not even close to "proving" anything conclusively yet- not via a tiny, tiny phase I. That's the first baby step on a 100 mile long road.