Yeah, you read the title right. Now, this isn’t my opinion alone (as I have seen variations of that statement on reddit, discord, and many other platforms), and I’ll leave the links to the posts at the bottom of this post.
Now to the point, D&D Beyond’s digital shop for Dungeons & Dragons 5e books is a serious scam as they make you purchase the hard copy–which is already $50–THEN they want you to purchase the digital copy. Wizards willfully ignores this, and to them its probably just them saying “You’ll get the product for cheaper and be able to play it online!”. But instead, to me its like “Give us your money and be grateful this is even here in the first place!”. First off, I can just use my physical version of whatever book I want to have on dndbeyond’s website to copy all the stuff that I couldn’t get from them unless I paid them more than $15 for a damn pdf.
So first off, there isn’t anything stopping you from copying into D&D Beyond, not even the law (since you own the material and paid for it), and second its free. And the first question you should be asking D&D Beyond is why the Hell are their Digital D&D Books $29.99 each?! That is a reasonable price for a pdf of that magnitude for a dmsguild product, but not a digital version of an official Wizards product!
Now, that being said, the rest of D&D Beyond is actually very helpful. The character builder and the compendium are a good source of 5e material, however really only the character builder is helpful as there is an entire website dedicated to the D&D 5e SRD: 5thsrd.org
Nerds R Us 