Why? - you can hold an EASA licence in any country in the world and keep it current as long as you meet the recency requirements.
How will you keep an EASA licence current? When your 6 monthly checks are signed up on a UK CAA licence??
No problem at all for UK residents flying for UK airlines.
Bearing in mind EASA’s approach, why would anyone in the UK give a monkey’s about another agency’s licence requirements? What do UK citizens have to lose??
Nothing!