I wonder if thats because there seems to be a bit missing from the ".htaccess" instruction in the wiki (but I may be wrong).
"Shouldnt" denotes a certain amount of plausible relativity due to the fact that just putting a "php.ini" file in the root directory of the web
A) runs the risk of exposing the file to people you'd probably rather not.
B) doesn't work on this hosting platform
The "php.ini" file should actually be located away from a directory that the httpd can find it; hence the cgi-wrapper solution offered in the wiki.
AddHandler php-cgi .php
..though I wouldn't place money on whether that's right because I pretty much exclsuively use my own PHP compilation and never use DH's.
Additionally you'll want to modify the wrapper command that invokes (execs) php like this:
exec /dh/cgi-system/php5.cgi -c /home/youraccount/php.ini
to force it to use your php.ini file. I would also highly recommend that you copy the distribution php.ini file in first as the wiki suggests and modify that copy.