They've been continually under-ranked because of a variety of reasons:
1.) It's Cincinnati, and recent history doesn't favor the Reds' development acumen. Since they've long been considered a relative failure, everything is seen through the lens of that failure. Senzel being injury-prone, India struggling early, Greene getting hurt, Lodolo struggling in his one pre-season start against Detroit-- it all drives perception.
2.) Many Red top draft picks have been HS players and have necessarily taken a long route to the big leagues. Stephenson was drafted in 2015, the same year as six-year veteran Alex Bregman. Robert Stephenson had a tortured development as well. Even Nick Howard and his yips took a relative lifetime to deal with. Sometimes, kids take an inordinate time to develop. Cincinnati just happened to follow low-round gambles (Phil Ervin) with a yips guy, with young kids.
3.) Last year's development was completely overshadowed largely because prospects didn't play against other squads. Cincinnati didn't get helium on, say, India because so few people did see him. (And the narrative that India is a bust was a powerful one in the industry.) (Same is happening, fwiw, with Greene and perhaps Lodolo.)
4.) Again, because of the pandemic and lost minor league season, no one was able to judge the effectiveness of adding a strong analytic department to prospect development. We saw some success with Antone and company at the major league level with Driveline, but we saw very little from the hitters. As a result, the narrative drove the perception. (As is often the case with national prospect divination.) With India's development (and perhaps with good news from Lodolo and/or Greene and/or Gutierrez), perhaps the narrative will change.
What's funny is that this cycle of super young top prospects will continue through at least two more seasons. Rece Hinds, Tyler Calihan, Austin Hendricks, and other recent high draft picks are almost exclusively very young in their developmental process. We'll have to be patient with them too. (Or we could just insist the Reds don't know what they're doing, and their minor league developmental system sucks.)