That's a very good question. I don't understand either why Binance, Coinbase, Crypto.com, Trezor, Ledger, BitPay, Bitrefill and similar companies don't advertise. Logically, they should be here but they aren't.
I can say a bit more about hardware wallet companies like ledger, trezor and few others, because I know people who contacted them for signature campaign promotion.
Most of them were not ready to invest amount of money needed to have serious signature campaign.
Best we got was small promotions and giveaways from Satochip and Bitbox, but maybe this will change in future.
I remember the time when Trezor team members and Keystone owner was active in forum, but they turned more towards twitter I think.