but there are things such as lightning explorers
they reveal many things, balances per channel, who the nodes connect to. they actually reveal alot more then the bitcoin block explorer does about individuals
Actually, you are right.
1ML.com is an example of such explorer. However, it is possible to open a private channel which is only known to nodes which maintain it. Such channel is excluded from routing outside payments since other nodes don't know that it exists. LND allows their users to open a private channel by adding
--private parameter while opening a channel. I guess it's only useful for people who often trade between themselves and don't wont other people to interrupt.
--private make the channel private, such that it won't be announced to the greater network, and nodes other than the two channel endpoints must be explicitly told about it to be able to route through it
i can also without LN make private payments. yep you dont need LN nodes.
people have been using multisig for years and doing things privately.
many exchanges have had multisig reserves between themselves for years without LN and without needing to broadcast every trade to a blockchain
people have actually done physical bitcoin trades (paper wallet and casascius coins) without needing to broadcast to a blockchain
in 2012-2013 i remember arbitraging between mtgox, btc-e and bitstamp without seeing bitcoin broadcast onchain