px per inch question

Question

Isn't it also a good practice to decrease px per inch ratio (or DPI I believe) in some cases?

As my question might not be really clear, few words what I have in mind.

On any website you can imagine there are photos at least one, logo, profile picture etc.

As long as I'm consider in many cases it is pointless to use 300DPI images (for examples avatars, profile pictures in conversation tab or anything like that where high quality picture at least in my opinion is just a waste of resources especially if someone is using mobile data) which is I believe consider as higher quality photo (and therefore it takes much more space than 72DPI commonly used in most cases described before)?
But of course if photo is showing perfect looking panorama anyone would use 300DPI as the difference might be visible in high resolution.

Yeah I do know that this question is connected to graphic design more than HTML but curiosity hitted me hard on this one.

I would like to apologize for eventual mistakes I've made during writing this question.

I hope that this question actually makes sense.

Answer 1

Pixel density varies very much from different devices. 300dpi images are the standard for print design, but are not used in web. The images are always based in the standard 72dpi, and sometimes a second version of the image twice big is included to be shown on high density screens.