When the description of methods in a scientific paper becomes optional.

I have just read a paper describing some very interesting tailoring of enzyme specificity on a P450 enzyme. I was, however, surprised to find that no description of the experimental methods was present in the paper itself, but was only available as Supporting Information. Upon examination of the instructions for authors in the journal I learned that, although being online only (and therefore lacking any space constraints), this publication enforces a 40-thousand character limit on the published papers and specifically states that the experimental section is optional. Traditionally, Supporting Information includes accessory data which would be cumbersome to include in the paper.  In this journal, it functions instead as a cumbersome way to access a vital part of information which should be part of the paper. I cannot even begin to understand why any reputable publisher would, in the absence of any printing costs, force their authors to split their manuscripts and "demote" the potentially most useful portion of the paper to the Supporting Information.
That's ACS: proudly claiming to "[publish] the most compelling, important primary reports on research in chemistry and in allied fields" while making it difficult for readers to have access to that same information.