Actually, yes it is a joke... even if unintended.

At Internet resolutions and sizes, you're unlikely to see the difference. Those sample images are way too small to offer anything definitive.

Also, a high quality, multi-coated filter is not likely to give any "issues" with a shot such as those in the samples: reasonable lighting conditions and the filter protected from any light directly striking it.

Poorer quality filters can effect image sharpness, amp up chromatic aberration, even interfere with auto focus.

High quality, multi-coated filters generally avoid those types of issues... But even the best can cause or increase veiling and ghost flare effects if strong oblique light strikes them.

They are simple facts:

1. Unlike film, digital imaging does not require UV filtration. It's already built into the camera itself.

2. Lenses are a lot tougher and harder to damage than people think.

3. It's sort of silly to think that a thin piece of glass is going to provide much, if any, "protection". Actually, the opposite can be true. A broken filter can cause damage.

4. Lens caps and lens hoods... most made of "high impact plastic" and bayonet mounted these days... both do a far better job protecting lenses than filters do. Somewhat ironically, if using a filter it's even more important to use the cap and hood, to protect the filter from damage and oblique light!

5. Lens hoods also have potential to improve image quality, might even help metering and autofocus work better... and so long as a hood is matched to a lens and properly attached, cannot possibly have any negative effects on images. The only reason to not use a lens hood is when needing to be so close that it gets in the way. Otherwise, it's just plain laziness to not use one.

6. Anything between the lens and the subject is going to have some effect on every image... be it Schott glass, window glass, a chain-link fence or just plain atmosphere.

7. Fans of "protection" filters will argue to the grave for their use, with no real evidence to support their claims.

8. There is more evidence of the opposite... that filters do little or no good protecting a lens. For example: https://www.youtube.com/watch?v=P0CLPTd6Bds

9. It's easy to store filters in your bag and have them handy, ready to use in certain situations such as blowing sand.

10. Damaged lenses can be repaired, sometimes at less or little more than the cost of a quality filter.

11. There are some rare occasions when a UV filter might help reduce visible atmospheric "blue haze" in images.

12. Who cares? It's their images that might be compromised for no good reason... not mine. So I like it when a competitor uses a filter! The cheaper and crappier, the better!