Nether Fortresses are ignoring "Generate Structure" setting at world creation

without structures you can still find giant nether brick walls in the nether

I expected to see a nether with no structures

What actually happened was I found giant nether brick walls

1. select create new world
2. choose creative
3. allow cheats
4. DO NOT choose bonus chest
5. choose superflat 'classic flat'
6. DO NOT allow structures
7. load the world
8. build a portal to the nether
9. enter the nether
10. near to where your portal spawns you will find giant nether brick walls