It does try to reduce what it can in low memory situations (less "pre" optimizations like prefetching, prerendering, even dns prefetches and stuff, V8 gets more eager to throw out "potentially unneeded" code, tabs get suspended and written to disk, heuristics can get shut off, etc...), but it can't change what the page does.

If a browser tab wants to store 300MB of data in RAM, or wants to throw a shitton of stuff at the DOM, Chrome needs to oblige.