Well yes, but it goes both ways. If you have ass cheeks for interior OL but a good LT you're not going to have a good OL. I'm not arguing that LG is more valuable than LT, just saying that really good LGs are still really valuable.
Truly elite guards hold their value. Quenton Nelson was the most valuable offensive lineman in the NFL by WAR in 2020. Zack Martin is always towards the top of the list as well.
We have this same PFF conversation every season. PFF grades are just a data point to take into account. The grades are accurate +/- 5 points. Meaning a player who grades out at a 60 for the season might be a 65 or 55 but he's probably not an 80. A player who grades out at 80 might be 85 or 75 but he's not a 60.
Not surprising after the NO game. As much as our WR core has improved from last season, we still don't have any great separators until Phillips returns. Burks has the potential to be but he's not a polished route runner yet due to his lackluster start/stop speed which is generally more important in route running than long speed.