MoneyWeek article on fractional shares in an ISA

I am writing a story this morning on HMRC stating that fractional shares aren't eligible for an ISA.

I am seeking financial experts/commentators to comment on this approach. 

What are the pros and cons of fractional shares? Who typically uses fractional shares? Is HMRC right to ban them from ISAs? Will this deter younger investors or those with less to invest? What are the alternatives if you don't have much to invest e.g funds etc

Many thanks

Marc