With an alternate timeline of events you have a degree of plausible deniability. In regards to the canon of the show and what we the audience know to be true. Since ENT is a prequel series it walked a tightrope of facts and sometimes contradicts what we know to be true from the series that preceded it. First contact with the Ferengi and Romulan cloaking devices being the biggest goofs by the ENT writers. Keeping the facts straight was compounded and made harder with the TCW and the different factions all trying to rewrite history in their favor and using races we the audience had never heard of to do it.
Creatively this is a clever thing to do if you can do it well. But the ENT writers didn't have a complete direction for where to take it so it kind of fizzled out and settled for being a post 9/11 allegory. It a lot of ways ENT resembles the current Trek movie franchise under Abrams. While Abrams completely shed the skin of previous continuity as far as look of the future and chain of events with races. Berman and Braga (from commentary's and interviews) were intent on keeping it all together as one big stitched together universe. Personally I think they should've used ENT as a full sequel to FC and have the prime universe be the TOS through VOY Endgame where B&B ended the 24th century series.