While somewhat true still, much progress has been made and the situation isn't the same as five years ago.
Furthermore, there's multiple ongoing efforts to bring seL4 closer to turn-key, such as Makatea[0], Genode[1] and sel4cp[2].
0. https://trustworthy.systems/projects/TS/makatea
1. https://www.genode.org/
2. https://trustworthy.systems/projects/TS/sel4cp/
While somewhat true still, much progress has been made and the situation isn't the same as five years ago.
Furthermore, there's multiple ongoing efforts to bring seL4 closer to turn-key, such as Makatea[0], Genode[1] and sel4cp[2].
0. https://trustworthy.systems/projects/TS/makatea
1. https://www.genode.org/
2. https://trustworthy.systems/projects/TS/sel4cp/