SableWyvern
Hero
"Supposed to" is, in my opinion, a very flawed way of looking at it, and suggests a third party had some right to dictate what happens at a private table. This isn't a Magic tournament rule or an MMO running on a public server; the only time anyone is "supposed to" allow a particular class or do anything WotC suggests is when they have agreed to do so.WotC says that 2014 characters are still legal in 5.5e, although as you say, individual DMs may differ. Hence "supposed to".
A DM should certainly make it clear what is and is not appropriate in their game, and gain buy in from players, but that's always the case.