That's exactly the point I'm making. It's rare for them to flat out reject people from entering a standby line. Look at FoP in DAK, especially in the morning, that line can stretch. At Rise, the boarding groups mostly keep the line inside. At points though, the queue can be filling most of the indoor portion, even though you waited for your boarding group to get called already. I'd guess there's about a 30 minute or so wait.
When they have a physical queue only, I predict the park will be more crowded because the queue will stretch, as you mentioned, and people won't be as quick to leave after 1pm. Moreover, there could be an increase in park hopping to DHS from other parks. We'll see though, I think Disney itself is watching this carefully.