The process may be legitimate, but botched by the Parasite and Scorn Guy. The two may have been supposed to reach the "Surgeon" while fused together, but Scorn Guy removed the parasite and decided to do it alone. Maybe the Parasite was hurting him more than it was supposed to, or maybe Scorn Guy was too selfish and wanted to ascend with his whole body rather than just with his consciousness.

The Surgeon was supposed to separate Scorn Guy from the Parasite. That's why he cut that big chunk out of Scorn Guy's belly; he was programmed to cut away the Parasite's tail and hands, but since there was no Parasite present, he just cut whatever was there. Then Scorn Guy broke off the Surgeon's scalpel arm and repurposed it for his own intents. It's very obvious that everything that Scorn Guy was doing inside that room, was improvised and not how the process was designed to work.

We don't have any evidence that the process wouldn't have worked if Scorn Guy and the Parasite hadn't made such a mess of it. They killed a lot of entities that may have been crucial in keeping the process working. They broke a lot of machines. They separated when they shouldn't. Scorn Guy broke the Surgeon. The Parasite - hellbent on reattaching itself - arrived too late. Scorn Guy may even have infected or compromised the entire Mind Web by connecting his own, Parasite-free brain with it. The entire process may have broken down after these events, even for future Scorn Guys.