I would hardly call him snubbed. He plays in a position England are stacked in (Rashford, Grealish, Foden), and it looks like Southgate has basically already decided his Euros squad.

Plus Southgate doesnt pick players on current form, he likes to give players a full PL season and seeing if the form continues into the next, good examples being Jarrod Bowen and Callum Wilson. This is something the National Team set up was very bad at doing ~10 years ago; picking players who were in form and then dropping them, whilst ignoring generally solid players. This lead to a very inbalanced and inexperienced squad, and inevitably the same old names had to play to keep any sort of consistency.

However I find it unlikely both Watkins and Nketiah will go, and Rashford’s form really needs to improve, so there is a chance.

Southgate has clearly just picked the squad he wants for the Euros. Harsh on players that are excluded, fortunate for out of form players, very effective during the actual tournament.