Could the logic surrounding formatters such as

https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Console/Helper/ProgressBar.php#L91

be made on the object instead of static on the class ?

It gets too hairy to define placeholders for a specific bar or overriding existing placeholders. Now this "global / static" situation doesn't really allow anything from the domain or live values to be pulled in unless the placeholder renamed for each bar. For example for the estimate when i am reading 2 files, one of 100MB and one of 1GB it can last 1 minute and 10 minutes, but after the first file the estimate is now 2 minutes total. With filesizes know the estimated placeholder could be rewritten for that one bar, but this isn't possible with static.