Well you also need to keep in mind that the OpenWRT guys sometimes make strange decisions. For the AR750s, the OpenWRT guys actually dropped it completely from their build tree, because they wanted larger kernel sizes, and the AR750s uboot didn’t currently support that. GL submitted changes very quickly, but the OpenWRT guys didn’t want to merge them, it took a long time, multiple months for anything to be done. With the S1300 it took them more than 1 year to merge support for it, when GL had patches submitted right after it’s release.
The OpenWRT guys also nearly dropped all the GL routers when they wanted to change from ar71xx to using ATH79, so they don’t always fix things to get them working, they rather just drop support.