Legally speaking, it’s probably possible. Practically speaking it almost certainly a guarantee that the company will never see outside investment. On every round someone would need to pony up the cash to fill that employees stock. Anti-dilution clauses exist, but they never work like that.
Such a privilege is also likely to be almost worthless - if the company succeeds and the round makes it worth more, you’ll win even with dilution. If the company doesn’t, then other clauses such as liquidation preferences will make your stock worthless, regardless of how much you own.
The difference is that if the company succeeds, an employee afforded this provision is guaranteed to make $X.
Without this provision, it's possible in many ways for the employee to be left with far less than $X, even if the company succeeds. In some ways <<<<<<$X.
Such a privilege is also likely to be almost worthless - if the company succeeds and the round makes it worth more, you’ll win even with dilution. If the company doesn’t, then other clauses such as liquidation preferences will make your stock worthless, regardless of how much you own.