I would expect most people to read code in their IDEs, where small amounts of type inference like this is fine because the IDE tells you what the type is.
I agree that if you spend a lot of time reading code in something like GitHub, not having explicit types is annoying, but seriously, who does that?
If the IDE only displays the type on hover, that’s a significant usability regression.
It also makes it harder to grep for usages of any given type. Of course IDEs could help with that too, but I don’t know any that provide that functionality.
IDEs don't always display every type in a useful way. Sometimes they just display an unhelpful alias which ends up being just as useless. Sometimes they display an incredibly verbose version with all the default template parameters written out, making it a nightmare. Sometimes they give useless results, like when you have a dependent type whose concrete type you know (imagine typename T::value_type vs. size_t). Sometimes they haven't even finished analyzing the code yet. I could go on. You should not be crippled without your IDE.
Can you compute elementary functions by hand? Why not? Why are you crippled without semiconductors? This attitude leads to never being able to use better tools. We can't leverage an IDE because then we're "crippled" when we don't have it, so we continue writing code as if it was the '70s and the best we have is ed.
I agree that if you spend a lot of time reading code in something like GitHub, not having explicit types is annoying, but seriously, who does that?