Why are all android web browsers unable to display PDF documents?

I just switched from an iPhone to a Pixel. Whenever I try to open a PDF document, the browser automatically downloads it and ask me to open it elsewhere. I don't want that; I want an in-browser PDF view. Also it's not specific to browsers: the Gmail app, the Telegram app, almost any app is like that. Do I need to install a system plugin/extension or something? Edit 1: can you "hack" the pdf feature into the webview by e.g. rooting the phone? Edit 2: as I understand from the answers it's the AOSP developers' intention to make the pdf feature unavailable, contrary to say legal reason with adobe?