Nonsense. Viagra et al, usually some form of Sildenafil is available in most pharmacies in Thailand. Sidegra is the Thai Viagra in the 100mg size, packets of four are about 225 baht. I bite them in half.
No pharmacy has ever asked for a prescription. It may be controlled drug, but it's completely out of control. Kamagra jell is also available everywhere. I've never heard of anyone having issues with bootleg ED drugs.
I don't know why anyone would post something so completely wrong. You wouldn't buy it from a street vendor because you don't have to. Jeesh.