Agree. What was s great simple interface has been fucked up by that new CEOs mandate to "Googlize" it over old code.
You can still go back to the original Yahoo mail. Just click on the gear in the upper right and then click on settings. You'll get a new window. Under 'viewing mail' at the very bottom are 2 radio buttons. One is for 'full featured' which uses javascript. The other is 'basic' which completely 'manual' - in the sense that you have to select what you want to do, like sort, and then execute.
I was switching back and forth between them because for about a year or so, the so-called 'full-featured' version wouldn't let you sort by sender. How fucked up is that? Now it's finally been added although about a month ago, they had to suspend some of the features.
I like yahoo mail just because I can set up junk accounts based on a root character string. But that's a premium feature. Unfortunately, some sites still don't like hyphenated email addresses so for those, I use junk gmail accounts.
I have a couple dozen gmail accounts but it can be a pain in the ass for long correspondence from multiple parties. So I forward all of the gmail accts to yahoo.