it would be wonderful in theory not to need a shadchan. however we are not malachim. the rambam says men should stay far away from women.
If every man/boy was able to get to know women/girls on their own many being overly tempted to do all kinds of avaros.
This leaves us little choice but to have a shadchan.
if someone is older and by chance knows someone single it’s no avara to ask them for a date(especially widows and widowers) but in general especially with young boys and girls its a terribly dangerous and naive.
there is a reason why we use a shadchan,and we shouldn’t be poretz gedder.