I don't know why the parent comment talked in such absolute terms, but these recent problems may be relevant:
https://news.bitcoin.com/hidden-lightning-network-bug-allowe...
https://news.bitcoin.com/mishap-sees-user-lose-30000-btc-on-...
https://news.bitcoin.com/hidden-lightning-network-bug-allowe...
https://news.bitcoin.com/mishap-sees-user-lose-30000-btc-on-...
The bug has already been patched, and had a limited userbase. The user who supposedly lost all his Bitcoin ended up not being true, vast majority was recovered. It's also worth noting that the user also deliberately went against various UI warnings that funds may be lost.