Feat chains that are 2 feats deep are ok, if the first feat already does the important thing and the second one only enhances it.
But anything more is bad. Remember whirlwind attack in 3.x?
Even worse though were feats as prerequisites for prestige classes.
I think Crawford is right when he does not want to overwhelm new players. In my experience, chosing feats without ever having played is not very easy, because they just don't know what is important.
In the same sense, it is also not easy for experienced players, as they often don't know what is important for this particular campaign. So if you notice, that a certain campaign is all about having unarmed combats*, you want to be able to take tavern brawler immediately and don't want to first take another feat.
On the other hand, if you want to be the best tavern brawler, I would not mind a second feat, that increases unarmed damage to d6 or d8 and gives some more benefits that are helpful. Maybe initialize a grab and do extra damage when grappling.
*just the first thing that came to mind.