We can't and Steam might be illegally do it: https://itch.io/docs/creators/quality-guidelines
Sales
Your project should not be constantly on sale
A sale is a special event when your game can be purchased for a reduced cost for a limited time. If your game is always on sale, then it’s not actually on sale. Update the price of the game accordingly. We want people browsing game sales to see things that are on sale.
In many countries it is illegal to misrepresent the cost of your product.
Avoid creating sales too frequently
Creating sales too frequently reduces the value of an individual sale. See the points from above.