I am a bit fuzzy here, but I recall Google having a deal with Twitter and access to the firehose.
I recall finding all kinds of specific tweets, by searching "string," etc.
This does not seem to be the case today.
This is important because you may be used to relying on Google searches to be exhaustive, and include tweets. Now it seems you have to go to twitter.com as well.
Search keywords in firefox make this easy. I can type "wiki train" into my address bar and it will take me directly to https://en.wikipedia.org/w/index.php?search=train From a usability standpoint it's just as streamlined as typing the same into the address bar and expecting Google to find it for you, except you don't need Google.
Googling everything by default is a bad habit, but one Google obviously likes to encourage. They want everybody to rely on them for everything.