At the end of the day, Flacco has had sweet fuck all in terms of receiving options in his career, when you consider what other teams have to work with. You're a Steelers fan who is spoilt with the Big Ben/Brown/Bryant trio so you wouldn't understand how frustrating it is as a fan.
Flacco may not have had elite top 3 WRs in his career but it's also a bit extreme to say he's had "sweet fuck all" as well. Boldin's failure to reach 1,000 yards was more because the offense as a whole was not terribly productive, not due to him regressing. He wasn't just a beast in the playoffs, he was a beast in the regular season too. And he's always been a fantastic chain moving WR, he's just been saddled with mediocre QBs since Warner retired so he hasn't been able to reach full potential. Just look at Larry Fitzgerald.
Also don't forget that when Flacco came in the Ravens had one of the best receiving backs of that time named Ray Rice, who was a great checkdown for Joe and I suppose the reason he earned the nickname Captain Checkdown. Sure it's not a WR, but it's still a very reliable receiving option.
SSS could still be a #1 option on many teams right now, even at his age. He's got the passion and leadership for it, and he's still in excellent shape. The fact is that Joe Flacco absolutely thrives with that type of WR, which is why Ozzie has actively sought those types out (Boldin first and then Smith).
I think what you're missing is that Joe Flacco's perceived lack of receiving options is
intentional, because that's how the GM and Coach have planned it out. They could very easily have gone out and grabbed a top 3 talent at some point, but they didn't because it wouldn't fit their style and it may not even be a good match with Flacco. And obviously it was a good plan, because the Ravens have a Lombardi under their belt and several playoff wins since Flacco arrived.
To your comment about Big Ben/Brown/Bryant, that's only very recent. When Big Ben was drafted and started playing in 2004, Pittsburgh had what, Heath Miller and Hines Ward? Hines Ward was basically SSS with less intensity. And after Ward retired Pittsburgh was relying on the likes of Plaxico Burress, Santonio Holmes, Mike Wallace and Emmanuel Sanders to be their #1s until Brown had his breakout. So yeah, I'm also not as "spoilt" as you think.