I would argue that UDP isn't broken. Networks which drop it indiscriminately are broken.
Not indiscriminate.
As Google was informed by network operators all along since 2014, ipv4 UDP is a major uptime threat via DDoS to access networks.
Access networks need controls to maintain uptime against the non-stop barrage of ddos attacks. I am sure you have seen the headlines and mails on this list, ddos is hard to deal with. Access network will use whatever tools are required to keep the pagers quiet and customers happy.
Google choose not to be sensitive to that, they were told where the landmines were, they choose to go on anyhow.