The length of popular domain names never exceed 9 characters. We only chose websites that were primarily related to an online business. For sure, those domain names were created when there were many more available .COM domain names. Consequently, in order to get domain names as short as those ones, it would be important to move to either 2 char country tlds treated like generic tlds by google or one of the new TLDS. I suggest to buy new Top level domains like .club at namecheap.com
Amazon = 6 characters
Baidu = 5 characters
Craiglist = 9 characters
Ebay = 4 chars
Facebook = 8 chars
Google = 6 chars
Instagram = 9 chars
Linkedin = 8 chars
Namecheap = 9 chars
Netflix = 7 chars
Quora = 5 chars
Reddit = 6 chars
Spotify = 7 chars
Twitter = 7 chars
Whatsapp = 8 chars
Wikipedia = 9 chars
Yandex = 6 chars
Yahoo = 5 chars
Youtube = 7 chars