you'll find that waiting on TE (and QB...) is actually most beneficial for your roster in a world where you can have 100% security in your picks.
is this why I'm relatively awesome at fantasy
At any rate, I think the best draft value you can get doesn't merely care about position average, or floor. It's also about how much better your pick is than the next-best ranked player(s) at the position in question when you're in the draft. That's your immediate opportunity cost: who are the next players likely to go off the board between your pick(s) and how much better are they than the next wave of players in that position? Taking Gronk 11th overall ain't hurting your RB prospects anymore than the guy picking 8th taking Julio Jones hurts theirs anyway, and I think we're past the days of making fun of people for going WR first (although it remains a point of discussion every season) when you're picking mid-round and all the top-tier RBs are already gone.
But I don't think you're even really disagreeing with me judging by that statement in the middle of your post there. Yeah, it's harder to draft TE1 and two borderline elite RBs than just grabbing a top-tier RB, a second-tier one and picking a random late-round TE later. Half the league can have two great RBs but there's only one Gronk, but really it all depends on draft position... and the oh-so-subjective perceived value of each player. If you're picking 11-of-12, the top-tier RBs and WRs aren't there anymore. So take Gronk and be that guy who gets to build a serviceable "TE1 / RB12 / RB13" team, because he won't be there in round 3, probably won't even make it through the guy wheeling picks 12-13. Better than taking RB8 and RB10 and getting dumped by everyone else having RB1 + RB12, RB2 + RB11, WR1 + WR5 and shit.
If everyone drafts "perfectly," then everyone's team should be roughly the same strength. The only difference would be minor discrepancies between certain tiers of players (RB1 + RB20 might be slightly better, or worse, than RB2 + RB19 and such). Of course, some people draft better than others and ultimately there's still a lot of luck involved with injuries and week-to-week fluctuations. Having the most accurate player evaluations, taking the lowest risks with the highest payoffs, and managing waiver wire priority (depending on settings) is what gives you an edge, but like Pokémon there are few guarantees.
I'm not married to the idea of taking RB first. My draft philosophy is pretty fluid but I did say that I prioritized my Tier 2 RBs over my Tier 1 QBs (Rodgers/Luck) and TE (Gronk), so obviously I don't disagree with you either that RB is a more important position in general. The floor for low-end QBs is pretty generous, and on the flip side the floor for TE is pathetic but pretty much every TE not named Gronk may as well be there so who cares. (Exaggerating, there's maybe 3-5 other TEs worth playing consistently over streaming the position.) RBs carry the biggest injury risk and arguably has the worst ratio of good starters to position slots (especially in 2WR and/or FLEX leagues), so the more you can stash the better insulated you are from catastrophe. If I don't get Gronk, I'll take my RB3 over my starting TE. Usually QB as well because there's no reason I can't wait when everyone else has already filled their starting QB slot... (I'm actually kinda disappointed Rodgers and Luck went two of the three picks before me in Round 2 of Smogon League, I never get to draft QB early.)
But as the argument for Gronk, while he's "only" as equally good as every other elite position player is relative to the average, the thing about TE is that even #2 is pretty close to average. The step down from RB1 to RB6 is gradual, in fact they're all so close that everyone has their own opinions every season on which of the top 4-6 dudes should be #1 overall. Brown isn't that far over the next 5-6 best WRs. After Gronk, the value of even the next best TE dives off a cliff. You
might hit an overhanging tree branch on the way down, named Jimmy Graham or Greg Olsen or Travis Kelce if one of them happens to step up, but don't expect a soft landing.
What say ye about my taking Antonio Brown #3 overall in Smogon League, son? I could've taken Lacy and had an elite but probably not the best RB, or I could take the undisputed #1 WR instead. The real crime was Huy taking DThomas/Hill on the wheel and leaving kd24 Forte. :[ Forte > Hill easy, huy man what're ya doing.