Except browsers aren't "curating" content specifically designed to keep you obsessed and checking it constantly, which commonly includes things that will make users feel self-conscious (which teens will OF COURSE be susceptible to).
Making or curating content people like to consume does not necessarily make something responsible for those thoughts. Television stations, Hacker News, video games, magazines, books, movies, whatever.
I'm not saying instagram can't be criticized or improved, I'm saying it's not as simple as just assigning complete blame of all suicides to the place or thing where suicidal thoughts first arose. It's simplistic and I don't see how it is helpful or will lead to actual improvements.
There is too much value in the curation business for an entity like google to ignore.