Blackbeard and his crew never destroyed Baltigo. Monkey D. Dragon destroyed it himself for tactical supremacy. Maybe someone tipped off Dragon that Blackbeard was heading to Baltigo. But Dragon destroyed Baltigo himself to make the whole world think that the Revolutionary Army would be recuperating from an ambush from Blackbeard,while he is really planning to invade the Reverie.
LEADERS SUMMONED FROM ALL OVER THE WORLD AND THE TACTICAL GENIUS OF THE MOST WANTED MAN
We know Monkey D. Dragon has summoned the leaders of the Revolutionary Army from all over the world for a meeting. Why? Dragon is gonna send some of the leaders to invade countries and islands whose heads would be attending the Reverie when they have left. The Kings would definitely want to return to their countries as soon as possible, which is not what the World Government wants. So they would send some of the Admirals and Navy officers to deal with the situation. In this way the security at Mariejois would be weakened. That’s when Dragon strikes and invades the Reverie with his top leaders(Sabo,Ivankov, etc…). The World Government would never expect it because they still think that Dragon was weakened by Blackbeard’s attack.
*Theory by pooperfuj