Is oline the best position to be heavy in high school recruits? You know in a year if they're going to be any good right? You go heavy on oline, light on WR's and RB's. Portal lineman out WR/RB in as needed.
Portal OL typically not very good; hard to project HS kids also but as you say, that means you need numbers.
You really can't count on getting great WRs or RBs from the portal either, though. There are definitely more of them, and more that were highly rated in HS. Highly rated HS WRs that end up in the portal, though, are usually misevaluated guys out of HS. They get to P5 where everyone is as fast as them and they can't cut it. Plus, you take a lot of portal guys you are also likely importing team culture problem makers.
Portal talent levels will be also dropping going forward because the extra "covid" year of guys competing for roster spots will be gone.
I think it would be a big mistake to count on the portal for filling a recuring portion of WR and RB rooms myself. That could have made sense during the Covid bubble but it won't now. Actually, have you ever seen a team that relies on a significant number of transfers do well for more than one year? I can't think of one myself.
I think the best way to go (especially from the culture perspective) is to take freshman classes on the large side across the board and have the self-discipline to process out guys who aren't in the rotation by true year 3. Then use the portal only for a VERY few guys to cover positions where you missed significantly in some part of the roster distribution, go after the top portal guys that fit those spot with your resources.