The Gemara on today’s daf argues that by listing ḥametz as something that is burned, the author of the Mishna is identifying with the opinion of Rabbi Yehuda who rules that the only method of destroying ḥametz is burning. In fact, the Mishna in Massekhet Pesaḥim (daf 21a) brings the opinion of the Sages that it is permissible to destroy ḥametz even by crumbling it up and tossing it in the wind or throwing it into the sea.
In explanation of this disagreement, an interesting suggestion is made by Rabbi Ḥayyim Soloveitchik in his Ḥidushei Rabbi Ḥayyim HaLevi (Hilkhot Ḥametz U’Matza). Rabbi Soloveitchik argues that these two positions depend on the basic definition of bi’ur – destruction – of the ḥametz. Is this a purposeful command, so that the very act of burning ḥametz is the fulfillment of a mitzva, or is the commandment merely a requirement to ensure that the individual’s property will be cleared of ḥametz? Rabbi Yehuda who is meticulous about the quality and means of destroying the ḥametz, requiring that it be burned, believes that the mitzva is actually eradication of the ḥametz. The Sages who permit any manner of destruction do not see the eradication of ḥametz as a commandment in itself, as it is merely the means to an end – the removal of ḥametz from the person’s property.
Although our Mishna presents Rabbi Yehuda’s opinion without comment, nevertheless the halakha follows the Sages, and ḥametz can be destroyed in any manner, although it is nevertheless customary to burn it (see Rema, Shulḥan Arukh Oraḥ Ḥayyim 445:1).