Not Battlefield.

actually i think he got a point there
the core gameplay loop of "spawn fight for an objective die repeat" doesnt really changed over the years and even then if you dig deeper inside that loop there are a difference for comparison in bf 3 or 4 there was a moment to regroup and breath after the fight for the objective even on the smallest meat grinders like metro and locker but in bf6 there is no time to breath even after death there are 5 second timer and you back in action again
this is regarding the gameplay loop

then he mentioned dogtags and easter eggs which i think falls under a bigger category of rewards 
in previous games even the older ones like bf2 or 2142 we had ribbons and medals system then in the next games they added assigments and customizable dogtags with unique design some of them tracked in game stats some of them just had a cool design and almost everything there could be earned through ingame methods
and what we have in bf6 
the detailed ribbons replaced by an ai generated accolades 
the medals thrown in the trash can
the assigment stayed but have nothing to do with reality most likely generated by ai too
the dogtags lost their unique design and just copy the ai generated accolade on a silver or bronze dogtag 
and what we got instead 
the player card with a customizable options of background icon title badge or sticker and dogtag it seems like a lot of options but in reality most of the player card costumization locked behind bfpro/battlepass/shop or just currently (and probably forever) unavailable
so instead of showing to the world what people achieved in game they show how much money they spend on the game

so what is really left in BF6 from the older games?

Sorry, but I find none of the things you mention to be particularly emblematic of Battlefield as a franchise. In reverse, the core gameplay loop of BF6 has been feeling more and more like a proper BF. The differences are elsewhere, and not necessarily always to my taste, but the core formula is very much there. 

well the zou zou mou zou and other movement glitches are a glitches and not intentend movement 
but about the rest all dogtags easter eggs and other stuff this is developers work time that needs to be paid 
and the more money spent on the actual game means less money left for the CEO bonus 
but to be fair thats not just BF of EA problem there are a noticeable downgrade in most games quality over the past years the developers just make games for money and simply stoped thinking about the actual gamers
thats just the new reality we should accept or quit gaming because as long as people buys the game and their **bleep** battle passes nothng will change