A recent trend in consumer electronics is that mobile devices are capable of displaying content in a high pixel density. The smaller screens of various tablets and mobile phones are able to display images at a high dots-per-inch ratio, and this often results in images on websites tailored toward regular display screens being displayed in a slightly blurry manner. Because of the significance of mobile phones in the electronics market as a means to browse the Internet, web owners may be tempted to incorporate larger images that are suited for high-DPI displays in order to cater to mobile customers.
However, having a web page use high-resolution images for what would be displayed perfectly fine on a standard screen is likely to make the website lose its ranking in the indexing algorithms of search engines. This is because one of the factors that influence whether a search engine is inclined to display a website on the front pages of a set of search results is whether a measurement regarding a website's pages called "page weight" is reasonably low.
Page weight refers to how much supplementary data and how many distinct files and scripts an Internet browser program needs to load with the web page itself in order for all of the page's content and functionality to work and display properly. Search engines reduce the ranking of "heavy" pages out of respect for the commonly held opinion that having to wait for each and every page on an otherwise standard website to fully load several megabytes worth of content is difficult to tolerate.
Optimizing the file size of the images used to enhance a website's aesthetic appeal is therefore a popular train of thought for web designers. This is why Scalable Vector Graphics are being relied on more broadly by web designers; unlike flat image files that have been previously exported from image creation programs, SVG files are essentially pieces of syntax that instruct web browsers to dynamically illustrate shapes and graphics natively. Web browsers can load SVG syntax much more quickly because SVG files are far smaller in comparison. For more information click here https://www.reddit.com/r/web_design/comments/92s3ho/why_are_so_many_webpages_not_optimised_for_high/.