The bill that proposed the 1920 Maine Statehood Centennial coin was introduced on February 11, 1920; the original bill that called for the 1921 Alabama Statehood Centennial coin was introduced just over two weeks later on February 28, 1920. The Treasury Department was asked to comment on each of the bills in order for Congress to understand if it had any objections to the commemorative coins.
Though both coin bills called for a commemorative to mark the 100th Anniversary of Statehood, a noteworthy difference between the two lies in the fact that the Alabama bill requested a 25-Cent coin and the Maine bill sought a 50-Cent coin. (
I've chronicled the journey of the Alabama Statehood coin here: 1921 Alabama Statehood Centennial - Redux and the Maine bill here: 1920 Maine Statehood Centennial - Redux.)In a March 20, 1920 Report from the House Committee on Coinage, Weights, and Measures, a letter (dated March 16, 1920) from the Department of the Teasury was printed. The Treasury's letter stated, "In regard to the coinage of the 50-cent piece [Maine] and the 25-cent piece [Alabama] I beg to say that, while the Department has no specific recommendation to make, no objection would be interposed should the Congress see fit to authorize the issue of such memorial pieces. - D. F. Houston, Secretary."
So, the Treasury Department can't be "blamed" for collectors not having the opportunity to add a 25-cent commemorative coin to their collection (it would have been the second of the series - after the 1893 Isabella). The "fault" was all on Congress and the House Committee on Coinage.
1921 Alabame Statehood Centennial Half Dollar
1920 Maine Statehood Centennial Half Dollar

For other of my posts about commemorative coins and medals, including more Quick Bits and stories about the Alabama and Maine half dollars, see:
Commems Collection.