not sure why the patch things are needed, but the only situation where you need the textures file is when you need the things to be placeable in the doom editor
you should be able to summon them ingame without the textures file
examples:
textures text with dummy sprites and dummy patch for use with 3d models where you dont need the actual sprites... then you can re-use MOD1-n for all your models again and again... this is a trick I learned by studying genetech
sprite MOD1A0, 64, 64 { Offset 32, 64 XScale 4.0 YScale 4.0 patch MODPATCH, 0, 0 {} }
sprite MOD1B0, 64, 64 { Offset 32, 64 XScale 4.0 YScale 4.0 patch MODPATCH, 0, 0 {} }
sprite MOD1C0, 64, 64 { Offset 32, 64 XScale 4.0 YScale 4.0 patch MODPATCH, 0, 0 {} }
the no frames thing also confuses me a little... but in general it behaves like this...
modeldef -> you can summon the model in-game either by script or console
modeldef+textures -> you can summon the model in-game either by script or console AND place it when editing a level (of its also assigned a thing ID and all that in decorate or zscript)