As IAmMe90 rightfully said, there are many reasons for this.
There is no way to verify a user's experiences with a certain source, or that if these experiences were good future ones will be too. We also have had many vendors themselves and affliates of vendors hyping up products here - if we allowed people to discuss vendors, they would likely cloud the reports with inaccuracy and lead to people buying impure and mislabelled products - now
that is counter productive to harm reduction.
Now an example of where it can happen with legitimate users. In the past I obtained some Mephedrone that was amazing quality etc, I told a real life friend, and they got some from the same source, they were then sold a batch that appeared to be cut and impure - it seems the once legitimate source had gone bad. This happens all the time. Luckily my friend was not hurt as a result, but someone easily could be, and it's not in peoples best interests to openly discuss sources in such a way - particularly when these threads get archived for long periods of time, and vendors do often go from legitimate to scammers.
I understand your concern, but we've had this rule for a long time, and it's not going to change unless we magically find some way of policing legitimate vendors. If you want to discuss the issue more, drop me or another mod a PM
Anyway, let's get back on topic.
A rather basic question of my own - when this chemical first came out, many people were expecting this to be like MDMA, which seems to have been vendor hype and not the case - are there any existing compounds it feels similar to?
Furthermore, how's the comedown/hangover with this compared to traditional empathogens?