Its all dependent on the tabulature, most ones I use are note for note accurate. No one I've ever met has used them for crutches, however, I don't know where you get that from.
Well yeah, you can't learn to improvise by playing something pre-existent. That's just a given lol.
I know a lot of people that robotically learn tabs and play covers skilfully, and then when it comes time to actually jam and be creative they have no idea what to do and they flake out.
How do you read tabs? I can't even make a lick of sense out of them
"TAB has six horizontal lines that represent the six strings on the guitar. The top line is the thinnest string (first) and the lowest line represents the thickest (sixth) string. The numbers that are placed on the lines tell you what fret to play a note." Apply this to your bass.
Also, remember if you're looking for bass tabs you're going to find a lot of four-string tablature, you can use these, but you have to take your low B into consideration or just ignore it entirely. The cool thing about guitar is that there's usually more than one way to play the same note.
But really, if I were beginning bass I would be watching instructional videos, learning scales, and just diddling around with it a lot - months before looking into TAB.