Ja. He clearly seems to be referring to the Hickman Revolution, when TSR's primary design orientation shifted to more heroic arc focused and less treasure-hunting. Culminating in 2E relegating XP for treasure to an optional rule.
I think that 1983 is probably the best year to "cut off" the original period of D&D, and also marks the end of the (first?) Golden Age of D&D for several reasons.
The following happened in 1983-
1. Gygax left for Hollywood and no longer was very involved in day-to-day and creative at TSR.
2. The original artists (e.g., Tramp, Sutherland) and the new artists (e.g., Otus, Dee, Willingham, LaForce) defined the aesthetic of D&D through 1983. But in 1982, a certain artist (Elmore) was added ... and his aesthetic along with others that were added (Easley et al.) began to define products. Simply put- you can visually see the difference that occurs.*
3. By 1983, "classic" AD&D was complete. The PHB, MM, DMG, Deities & Demigods, and MM2 were out. The World of Greyhawk was done. All the classic modules were complete...
1978: B1, D1-D3, G1-G3, S1
1979: B2, S2, T1
1980: A1, C1, C2, Q1, S3
(Note- those are all the modules for those years, and all, for various reasons, are considered classics)
1981: A2-A4, B3, U1, X1 (also I1, L1)
1982: B4, I3, S4, U2, WG4 (DON'T SAY IT!), X2 (Also I2, N1, X3)
1983: This marked the transition year, with the release of old Gygax material (EX1 and EX2) as well as Ravenloft (I6) among others.
*You can see the changeover occuring in1983, with the cover of the MM2, which is the first hardcover AD&D book that you could look at and say, "Um, one of these things is not like the others." Then, of course, there was the release of Legends & Lore. So 1983 definitely marked the
last year.
4. By 1983, you had the Moldvay/Cook Basic D&D, but did not have Mentzer BECMI.
I would argue that 1983 was the last year of one period, and you already see a transition. From one art style and aesthetic to another, so the game is visually changing. From one target market to another (marked by the transition from Deities & Demigods to Legends and Lore). And, as pointed out, from play style to another (as shown by the release of EX1 and EX2, which are gonzo OD&D modules to I6, which is a Hickman adventure).
By 1984, with the release of Dragonlance and the complete conversion of the aesthetics, the conversion is pretty much complete.
IMO, YMMV, etc.