iso 8859 or escape sequencies?

Sun, 10 Apr 1994 16:22:37 EET DST

Is there a reason to use the html "escape-sequencies" (&oumlaut for |
etc.) for characters that are also in the iso 8859-1 character-set? Are
there browswers that do not support the full iso8859 character set but
do support the escape-sequencies?
-Timo H