SIEM + EDR vs. XDR: What Are the Key Differences?

The author of the post is wondering what the key differences are between using SIEM + EDR and an XDR platform. They express skepticism towards some vendors' descriptions that present XDR platforms as a one-size-fits-all solution for all typical SIEM and EDR needs. The author wants to know if anyone has practical experience with XDR platforms and can highlight their shortcomings compared to popular SIEM tools.