Red Hat had given a lifecycle for CentOS 8 with an EOL in 2029. IBM acquired Red Hat, and promptly announced they were reneging on this schedule. Given that the primary draw of CentOS/RHEL are long-term, reliable, well-supported, stable operating systems, users were... displeased.
CentOS stream is primarily intended to onboard users onto RHEL, which is undesirable when nobody trusts Red Hat to keep their word now.