Text mode doesn't work on some sites because it can't identify the content. Furthermore it turns the page in a kind of text only ebook whilst text reflow works within the original page.
Reader mode is a workaround, text reflow is the solution. It a reason to use Opera on Android. I wonder if it's so hard to implement that nobody else coded it.
Firefox on Android used to have text reflow, then they removed it. Then the crappy extensions were made. I used to use text reflow on Conkeror (Firefox based) on desktop, but a year or two after they disabled it on Android they removed it from Firefox. I agree, I also use Opera on Android, for this feature.
Reader mode is a workaround, text reflow is the solution. It a reason to use Opera on Android. I wonder if it's so hard to implement that nobody else coded it.