Survey of implementations to see which treat ' as a delimiter that terminates a symbol:
I tested (list 'a'b) on 42 Schemes.
Returned (a b): Racket, Gauche, MIT, Gambit, Chicken, Scheme48/scsh, Kawa, Chibi, Chez, Vicare, NexJ, STklos, KSi, SigScheme, Scheme 9, BDC, XLisp, Rep, Oaklisp, Spark, Owl Lisp
Returned (a'b): Bigloo, Guile, SISC, SCM, Shoe, TinyScheme, Dream, S7, Schemik, Elk, UMB, VX, Sizzle, Inlab
Syntax error: Vicare, Ikarus, Mosh, IronScheme, SXI, MScheme
I suspect that a lot of implementations think it's simplest to just gobble up what they see until they get to an unquestioned delimiter.