Teasers in newspapers are supposed to whet the appetite for the story. In some cases they are click bait to trick users into loading more advertisements. Scientific abstracts should tell the reading whether it is worth reading at all, allowing the researcher to cover more material in an efficient way.
A common thing in newspapers or blogs is that they have teasers. That is a paragraph which serves as an introduction and makes you want to read the remainder of the text. Common schemes are to include something like "a solution is found" or "number 4 will surprise you". They specifically withhold some piece of information to make you read the whole text. In online magazines you usually have to click on the headline and then the whole text loads on a new page. This generates another advertisement impression such that the publisher earns money.
It is okay to have a teaser text to catch interest and whet appetite to read the whole story. Lately some magazines have made those things downright click bait where it was not only a buildup of suspense but outright manipulation.
The scientific abstract one finds in research papers is in stark contrast to this. The abstract is meant such that the reader can decide whether he actually wants to read the paper. It was especially useful when access to the full paper was hard but you could get the summary of abstracts, like on a CD. This way you can browse millions of papers by their title and keywords. If you find something of interest, the abstract will quickly tell you whether you need to read the paper. The consequence is that the abstract should give everything away in a few lines. The goal should be that the reader does not need to read the paper any more.
I try to do the same here on the websites. Often enough the reader will already be familiar with the topic. Why should I waste the time by stretching the introduction to trick the reader into reading the whole thing only to be disappointed in the end? What I rather want is to describe the problem and the solution in a short way. If that is what the reader wants, he can be sure that it will be worth his time reading the article. And that is totally worth having less people reading the articles in full.