Microgaming initially enforced a one alias per player for the whole network policy. It was the OPERATORS that lobbied for the change whereby players could have one alias per skin, and thus multiple entries in tournaments. Far from not being allowed, operators pressured Microgaming into allowing it. The motive at the time was the big network "Grand Slam" tournament, where the top prize was $1,000,000. Casinos wanted to be able to boast that it was won on their skin, and they realised that they needed to attract the "big names" in terms of tournament players to play at their skin. The one alias policy meant that once a top player had been registered at a competitor, that was it, so the change was made so that several casinos could target players they wanted with a free VIP pass to the tournament (I got 4). What we have now is the fallout from this, and possibly some unintended consequences, such as multiple entries into operator specific tournaments that are designed to give money away, rather than make money through buy ins.
When it comes to multiple entries into the 999 continue tournaments, operators actually BENEFIT from a player keen to throw money into hundreds of continues on more than one alias, so they are not going to object, let alone act against it because other players have complained. In fact, complaints about multiple entries in bought tournaments have been made for years, the operators know full well it is going on, but choose to allow it.
If the operators wanted changes, they would simply have to get Microgaming to revert to the initial idea of a single network alias, but they probably won't go this far. What they COULD do though is implement a one alias per operator policy, so that for example, a player with 32Red group would only get a single alias across all 4 skins. This would enforce ONE entry to the local freerolls, and ONE entry into things like the locally run 10K pot 999 continue tournaments. It would STILL allow multiple entries into network events, so if there was ever another "Grand Slam", individual operators could still target the top players with free VIP entry, and said players could still play one alias per operator, giving each operator the best chance of being able to brag that the top prize was one by a player on their brand.
32Red could also implement "cross play" on their 4 skins, restricting players to a single sign in that works at all 4, and closing the old duplicates down. A side effect of this change would be to force a one alias across all 32Red brands policy for the tournaments.