DOI code is a digital code just to make it easier to find articles on online sites. With this code, you can write only one code instead of writing the full name of the author of the work, the name of the work and the date of publication in the reference. Of course, in print, transferring this code and searching for it is hard and difficult to find it, unless you download the article online and transfer this code, which is in the references section, to article search sites. Of course, having this code It can increase the traffic and read the article because instead of sharing the name of the article and the author with others, you only send a link.
Therefore, we find that the existence of DOI code has no scientific and credit advantage for articles and magazines and is only for use in the digital and online world. Therefore, magazines that have online and digital printing can use this code.
However, having such a code is better than not having it
Digital Object Identifyer DOI of a published article is just a number that stands for the hyperlink. This make it easier to easily access the report on the publisher's page.
You have used a word in your question which is 'value'. This word has different connotations for different people. The value of a scientific paper is usually judged by the volume of its contribution, importance of its contribution, the changes that the paper brings in, its innovative aspects, its presentation and many other aspects. I personally judge the value of a paper on the basis of the further areas of research that it instigates. I neglect all other factors while judging the value of a a paper. Its a tremendous bad habit. I am trying to overcome it but frankly I have not been able to. This evening also I was going through a paper and was doing the same to judge its value.
DOI helps you to locate a paper. If you ask the question directly, then the obvious answer would be that DOI has no connection with its value. I also support this idea. But it is also true that accessibility of a paper or the chance to come across the paper, while searching for it can be increased if it has DOI.
I see young researchers of the current generation giving a lot of value to DOI. So I can say that traditionally a scientific paper without a DOI number carried value. In fact, its value never had any connection with the DOI. But nowadays a new trend is starting among young researchers, particularly those below 30 years of age. They think that a scientific paper without DOI does not carry much value. In the next five to ten years when this generation will reach important positions in their research careers then they will spread this message. As a result of this, the possibility is that this trend will start.