There's an easy check on whether something is a new edition: Is the existing Player's Handbook (in this case) still usable in a new game or has it been replaced by a new version?
With Essentials the PHB 1-2-3 were not replaced by these books - they were add-ons, not revamps. Having a different design philosophy is what made them interesting but it did not render the prior options obsolete.
Contrast this with other (A)D&D editions:
2E: New PHB etc, old one no longer in print, rules changed significantly, classes completely redone.
3E: All new books again, rules changed dramatically, classes completely redone
3.5E: Books replaced here as well, classes modified, many spells and some mechanics modified. You could use a lot of 3E material with 3.5 (and we did) but they did replace the PHB and assumed in new material that PCs were using the newer mechanics so it certainly counted in my opinion.