At this point the web is about as complex as an operating system in terms of complexity. That needs really strong specific standards in order for it to work, and in turn projects like web browsers are huge and complex.
If someone wanted to build a web browser that only followed the simpler parts of the specifications, it wouldn't work for many websites* and people would not use that browser.
*Whether or not sites need to be so complex is another question entirely, but the reality right now is that they are
It does matter. It's safer for everyone if cyclists travel side by side in one lane because then the car driver has to spend less time in the oncoming lane to complete the overtake. A long string of bikes takes more time to safely pass.