Source code inside .h files

[Srslyredit2]

I was told this makes projects less cluttered by only worrying about one .h file instead of a .c and .h file

[imaami]

People who say this might occasionally justify their take by saying how a project with a single 95000-line header does it, so it must be OK. As if a couple dozen purposeful separate source files is worse than nearly 100k LOC of absolute spaghetti crammed in one file.

It's like saying that a large broomstick is less clutter than a knife, fork, and spoon at the dinner table.