This is a really stupid thing. Right now you can either open your tabs from bookmarks 1-by-1, or you can “open all”, but if it so happens that all the tabs in the folder open to the same website then you can get an (somewhat understandable) IP-ban from that website.
How about another option besides “open all” that technically opens all the tabs, but doesn’t actually connect to the website for that tab until you switch to that tab? Or even better, just put some simple limitation on how many of the tabs are loaded at once (especially if they are on the same domain), and then just take it easy and don’t load them so aggressively and fast that the website thinks you’re attacking them with a DDOS.