The scientific method is based on empirical data and the replicability of those experiments used to collect this data by third parties. However, in Human Computer Interaction (HCI / CHI) the ability to replicate experiments is not possible because there are no peer reviewed routes for data publication. This inability to replicate experiments due to a lack of public data means that HCI does not strictly follow the scientific method, and as such is sometimes seen as not rigorous.
But DE has been causing a lot of polarisation with the W3C and the Web Community in general but as of WWW2010 it still seems to be on the cards. Now it seems to me that supporting DE is going to be incredibly difficult, incredibly prone to errors, and incredibly easy to miss-use.