Are you a global company? Do you want to sell your products in more than one country?
Are you in a fix whether the same marketing strategy would work in different countries?
Whether the same advertisements would work in different places?
Whether the same key words would work in different countries?
Do you know whether your target population searches in English or native language?
Do you know that Google isn’t the leader everywhere? Yandex has 62% market in Russia, and Google has only 26%,
Bing has ~ 16% market share in US, Baidu has ~80% in China.