I haven't looked into this stuff, but...
The only thing that makes sense to me would be drawn from my experience with asphalt sealer.
I'm going to ASSUME (dangerous, I know) that it replenishes the shingles oil content while sealing it from the suns rays and other possible contaminants.
This is compared to a parking lot sealer which protects from spills of all kinds, keeps the asphalt from drying, and protects from UV rays.
IF this is what it accomplishes, theoretically, it's not a bad idea....as long as it works. It could potentially extend the life of shingles quite some time.
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