Well, IMO, that is not exactly true. You can plug an Omega/Encore plug just like any other breech plug, if you do not do your plug maintenance. It can start hang firing in as little as 8-10 shots with the hottest primers and heavier projectiles. Certainly not a magic number but in the right humidity along with other factors will have an effect on the number of shots you can get off.

The longer the projectile takes getting out the bore and the more pressure that BH creates the more blow back enters the flash channel of the plug.

The other fact that goes more along with what you might be addressing is that if you are a hunter or just an occasional shooter, the Omega/Encore factory plug is a winner. The only factory one that might be better is the flat faced Knight Vision NFPJ plug. In either case you still need to do the plug maintenance thing hand drilling the flash channel out.

Changes in the plug and the changes that I think you will see in the future can significantly delay a significant amount build up in the channel.