People wondered if Luffy deserves to earn the title of Pirate Emperor and a 1.5 Billion Berries Bounty but there might be an alternate reason why the news reported Luffy in such a light.
Luffy is a serious threat to the world: he has defeated 3 Warlords, destroyed Enies Lobby, declared war on the World Government and broke in and out of Impel Down with a large group of criminals and brought them to Marineford. He also infiltrated Big Mom’s territory, Totto Land, where he defeated Charlotte Cracker and Charlotte Katakuri, two of her Sweet Commanders and escaped.
Not just that, he now has a Grand Fleet of pirates, he is the grandson of Monkey D. Garp and the son of Monkey D. Dragon as well as being Sabo’s brother, he has allied himself with Trafalgar Law and is gaining many countries as allies and has friends like Silvers Rayleigh and the Yonko Shanks.
In his crew not only does he have very powerful crew members but some of them have strong connections. Sanji is a Prince of the Germa Kingdom, Franky is a student of Tom the man who built the Oro Jackson and all though he destroyed the blueprints he might still hold the knowledge to built Pluton; Ussop is the son of Yassop, Nico Robin is able to read the ancient writings and can actually find the One Piece and finally they now have Jinbe a former warlord.
As son of Dragon and brother of Sabo Luffy has the Revolutionary Army as a likely ally; with Jinbe the Sun Pirates are now also allies to the Straw Hats, the World Government might not be fully aware of Sanji’s relationship to his family so they could count them in.
The point is that Luffy holds a lot of power and fighting him might not be a good idea. Instead the plan should have Luffy killed in a war against the rest of the Yonkos.
By having Luffy announced as the next Emperor it angers Big Mom and Kaido.
The World Government might also be interested in Wano but do not wish to invade the country and start a war. Instead their plan is to have the Yonkos kill each other or injure each other enough and have them damage Wano in the cross fire and once it’s over they will invade Wano and take over as well as take out 3 big named pirates in the world.
*Theory by Sniper king ussop