In the early 2000s, some web developers began to question why Web authors ever made the leap into authoring in XHTML. Others countered that the problems ascribed to the use of XHTML could mostly be attributed to two main sources: the production of invalid XHTML documents by some Web authors and the lack of support for XHTML built into Internet Explorer 6. They went on to describe the benefits of XML-based Web documents (i.e. XHTML) regarding searching, indexing and parsing as well as future-proofing the Web itself.
In October 2006, HTML inventor and W3C chair Tim Berners-Lee, introducing a major W3C effort to develop new HTML specification, posted in his blog that, "The attempt to get the world to switch to XML … all at once didn't work. The large HTML-generating public did not move … Some large communities did shift and are enjoying the fruits of well-formed systems … The plan is to charter a completely new HTML group." The current HTML5 working draft says "special attention has been given to defining clear conformance criteria for user agents in an effort to improve interoperability … while at the same time updating the HTML specifications to address issues raised in the past few years." Ian Hickson, editor of the HTML5 specification criticising the improper use of XHTML in 2002, is a member of the group developing this specification and is listed as one of the co-editors of the current working draft.
Simon Pieters researched the XML-compliance of mobile browsers and concluded “the claim that XHTML would be needed for mobile devices is simply a myth”.