This links to the page where you can find a game and play.
OGS has other pages for other activities like forum, chat, puzzles… With according names.
Ladders and tournaments are pages where you can play too, but separated from the play page.
There is no need but a choice to have made this page as not everyone come just to play (for example). There are many ways to organize a go website.
But some users think surely like you and would like better a direct access to the find a game features.
In fact the homepage feels a bit empty in my taste; there are some more topics in the forum discussing about the organization of the site. Try the search.
You can read this topic
For a light and quick interface there are two OGSapp for mobile phones which may satisfy you more (see topics in the forum), one for android one for iphones.
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