Mechanics purposefully removed from LFR versions of encounters do not render the LFR encounters unable to teach players an idea of what to expect going forward into other versions. Yes, other versions will have those omitted mechanics. Yes, other versions will have less room for error/be less forgiving for mistakes. LFR isn't built specifically as a teaching tool - but it becomes one by experiencing fights over and over, and gives one a chance to obtain gear so players might actually be able to pug into normal versions (and upcoming flex versions) of content.