What you are referring to if I understand you correctly is mipmapping.
Unreal uses .exr textures and need to be set manually (https://docs.unrealengine.com/5.0/en-US/image-sequence-mipmapping-in-unreal-engine/)
Unity can generate them for you using their "Texture Import Settings Inspector" (https://docs.unity3d.com/Manual/texture-mipmaps-introduction.html)
In general as an asset "seller" on a marketplace, it's just easier if you provide the highest level of texture format and then some extras for low resolutions (same name, same format for 'hot-swapping'). Since some artists will use the one that is useful for their project or just default to LOD if they understand the process and your textures are higher quality or equal to the quality they require.
To answer your question 'are you spinning your wheels", yes, if you are doing 14 images in different variations. No if you provide a 4k and 2k texture. This is what I do since the artist who buys your model has a good understanding of how they intend to use it and if they need mimapping at all. If they do then you have already done your job, it's now up to them to provide extra levels for their own clients.
It's easy to get deep in the weeds on this stuff, and sure you can provide 2 basic scenarios which could be beneficial to them (as above). But the important part of the entire process is getting feedback from your clients, do you need extra things, do they help your workflow etc? Unfortunately as long as I have worked in studios myself, and sold assets most people either give you a thumbs up or down, that doesnt tell you much. So if you have other contacts who use your assets who have more valuable information then sure incorporate that, until then you can only do your best.
