I always thought Anders' approach to live vocals is "tbh I can't really do this shit, so might as well fuck around. The people in the crowd seem to enjoy it." It's cringy, but it is what it is.
ngl, I thought IF was going to break up within two years shortly after ASOP came out. Not because I dislike the album or anything. Just a gut feeling. I'm legitimately surprised they's still going ten years later. At this rate I would expect Dark Tranquillity or AtG to split (again, in AtG's case) before they do.
That has 100% been Anders approach to live vocals. He's never put any serious effort into improving his clean vocals. Recently he has switched to lower growl but I think that's more out of necessity than because he wanted to make the live performance sound better. From recollection he only started going to a vocal coach around 2016 when Battles came out - and judging from live performances he didn't get much out of it as he sounds no better now than he did a decade ago. In fact I would argue he is worse. At least back in the day he actually tried to sing the choruses to 'the hits' even though he sounded like shit. Nowadays he just growls 95% of the songs or doesn't do any vocals and expects the crowd to sing (he does this a lot for Where the Dead Ships Dwell).
If there was ever a time for IF to call it quits it would have been after SOAPF. That would have been a great album to go out on. If Hipster & Bjorn had then decided to do some experimental stuff and released SC/Battles/ITM under a different band name then whatever, but of course they both know that SC & Battles especially would have gotten zero interest without the In Flames name attached to it.