[ascar]

If the next number depends on the previous number (like with wyrand and many others) it can't be simdified.

You could simdify computation with different seeds tho, which might be fine for many purposes. However at that point it's also a custom implementation with a different number sequence than the non-simd version, which isn't the case with a SIMDified MT.

[adgjlsfhk1]

Also xoshiro generators are enough cheaper than MT that even if you couldn't simdify it, you could keep 4 and get run the 4 together in SIMD to get 4 outputs way cheaper than 1 SIMD MT.

[galangalalgol]

It looks like xorshiro was SIMDified in a paper linked in abother post in this tree.