Registering for things on the Internet is dangerous these days
Back in the old days (say up through the middle of the 00s), it was easily possible to view registering for websites, registering products on the Internet, and so on as a relatively harmless and even positive activity. Not infrequently, signing up was mostly there so you could customize your site experience and preferences, and maybe so that you could get to hear about important news. Unfortunately those days are long over. On today's Internet, registration is almost invariably dangerous.
The obvious problem is that handing over your email address often involves getting spam later, but this can be dealt with in various ways. The larger and more pernicious danger is that registering invariably requires agreeing to people's terms of service. In the old days, terms of service were not all that dangerous and often existed only to cover the legal rears of the service you were registering with. Today, this is very much not the case; most ToSes are full to the brim of obnoxious and dangerous things, and are very often not in your benefit in the least. At the very least, most ToSes will have you agreeing that the service can mine as much data from you as possible and sell it to whoever it wants. Beyond that, many ToSes contain additional nasty provisions like forced arbitration, perpetual broad copyright licensing for whatever you let them get their hands on (including eg your profile picture), and so on. Some but not all of these ToS provisions can be somewhat defanged by using the service as little as possible; on the other hand, sometimes the most noxious provisions cut to the heart of why you want to use the service at all.
(If you're in the EU and the website in question wants to do business there, the EU GDPR may give you some help here. Since I'm not in the EU, I'm on my own.)
Some Terms of Service are benign, but today ToSes are so long and intricate that you can't tell whether you have a benign or a dangerous one (and anyway, many ToSes are effectively self-upgrading). Even with potentially dangerous ToSes, some companies will never exercise the freedom that their ToS nominally gives them, for various reasons. But neither is the way to bet given an arbitrary company and an arbitrary ToS. Today the only safe assumption is that agreeing to someone's Terms of Service is at least a somewhat dangerous act that may bite you at some point.
The corollary to this is that you should assume that anyone who requires registration before giving you access to things when this is not actively required by how their service works is trying to exploit you. For example, 'register to see this report' should be at least a yellow and perhaps a red warning sign. My reaction is generally that I probably don't really need to read it after all.
(Other people react by simply giving up and agreeing to everything, taking solace in the generally relatively low chance that it will make a meaningful difference in their life one way or another. I have this reaction when I'm forced to agree to ToSes; since I can neither meaningfully read the terms nor do anything about them, what they are don't matter and I just blindly agree. I have to trust that I'll hear about it if the terms are so bad that I shouldn't agree under any circumstances. Of course this attitude of helplessness plays into the hands of these people.)