We have inherited from analogue books the aesthetics of complete justification, we find it in most of the books on our shelves. The absolute order, elegance and peace it conveys leads us to a much more harmonious and controlled place, but the truth is that this characteristic was left behind when our environment was digitalised and we started to create online content. A new medium gives way to new ways of designing and understanding space, as well as adapting typographic composition to this medium.
A new era of communication in pixels is no longer so controlled, we no longer measure the millimetres nor can we control the position of each letter, the responsive world creates a new way of understanding space in the design of our website.
The main difference between designing a book and designing a web page is that we stop controlling each parameter and we start to understand that, when we apply a complete justification in web design, the space of each line will be automatically calculated and, depending on the width of the column, the words will be distributed in the best possible way to fill that line, thus creating large white rivers* as we can see in the following example.
*We call white rivers to the spaces that are generated in a paragraph between words. Something very unsightly that on a web page can vary depending on the width of the column.
Full justification on the web is not only an obsolete and not very aesthetic resource, it is also not very functional as it prevents the user from being able to make a smooth and pleasant reading of it. It is true that nowadays there are native technical solutions for browsers such as hyphens, but their precision is far from that of text editing programmes for printing, where each block of text can be adjusted individually according to its position on the page.
This desire for control comes from the need of many people to see the right side of the columns perfectly aligned, something that, once overcome (see the column of this post), is nothing more than a feature of a paragraph ready to be read and understood. I am sure that while reading this text you have not had any problems, you have been able to read quickly without getting lost and without noticing the composition. As it has been said many times in the design world: "Good design is invisible".
In short, let's embrace left (or right) justification of texts with enthusiasm, but avoid using full justification in web design. Your website will enjoy proper legibility and look much more modern and up-to-date.
Full justification on the web is not only an obsolete and unaesthetic resource, it is also not very functional as it prevents the user from being able to read it fluently and enjoyably.