Did you know that we have the thinnest skin on the eyelid with 0.8mm? Which is why a "disappears after 1-2 years..." is very unlikely here. Personally, I am not a supporter of a pigmented eyeliner, however, I am a big fan of a pigmented eyelash line!
Unlike eyeliner, eyelash thickening only thickens the hairline, which makes for a more open look and makes you look fresher in the morning. Another aspect is that you can also fade an eyelash line thickening without hesitation, if you should decide against it at some point.
Why I don't offer eyeliner? If you decide to have eyeliner, you will have it forever. Unlike eyebrows, for example, you can neither have this part of the eye lasered nor work with a remover, and an eyeliner that still opened the eye at 25 can also make it look droopy at 55.