Because the largest russian imageboard (2ch.hk) is controlled by russian oligarchs and there was recently a law about punishment for "fakes". Also, now it is totally owned by kremlin trolls. Lakhta doesn't even hide it's presense and and writes propaganda guides in OP-posts of most popular threads. Often they even call to write claims to police for threads that doesn't fit government position.
<blockquote class="twitter-tweet"><p lang="ru" dir="ltr">Если будут уголовные дела за т.н. "фейки", то сайт я закрою. <br><br>Простите ещё раз, я до последнего бился, но здесь уже всё.</p>— Nariman Namazov (@abunyasha) <a href="https://twitter.com/abunyasha/status/1499327363661840386?ref_src=twsrc%5Etfw">March 3, 2022</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
Tweet related - admin of 2ch.hk says that he was fighting for the site as long as he could, but lost. And he is going to close the board if there will be crimminal affairs opened against of it.
Also, take into account that servers are located abroad of Russia and connection to them may be lost because of sanctions.