Why is this? Are developers depending too much on package managers to install 3rd-party library to add things like this without checking if they actually work? Do companies prefer to take the risk of getting bombarded with spam instead of adding an inconvenient steps to their legitimate users with a captcha? Are people taking web security for granted with mainstream frameworks?
[1] https://invite.slack.golangbridge.org/
[2] And ironically opened another bug (which is already fixed) where you could send an underscore as the value for the captcha and take down the Heroku instance with the second request, something that I never understood until they (somehow) fixed it.
[3] https://github.com/rauchg/slackin
[4] echo '[email protected]' | sed 's/\+.*@/@/'