As you well know the action of a turbulator is different and because of that many suppliers use smaller tanks with turbulators--or use more resin. I believe one of the other posters on this board has posted that he does the latter.
There are many approaches to water treatment and very few "requirements". Rather there are practices, good practices, etc. Just because you do things one way does not mean that there are not other ways and just because someone does things differently than you recommend does not make them wrong.