Not totally true, MEP could raise a motion that would then go down the process and eventually come up as an amendment that the EU member countries would have a final vote upon and. But I don't foresee any wanting to block something as fundamental as that.
Just sad that that initiative has just never happened, actually it exacerbates me personally even though it has no effect upon me whatsoever; Just irks me as one of those great unfairness that could and should be fixed even if too late now for the current utilisation, but any future use. Though I'm wondering if the EU likes it as it stands so it will cause friction and allow that friction to be laid upon those who action article 50. Who knows, beyond it's a massive oversight upon peoples rights from a collective that trumpets, peoples rights.
Though we do live in strange times.