I mostly use PayPal when there's some kind of promotion that gives me an incentive, such as extra credit card rewards, or a cash back offer. I think a lot of people find it convenient to use PayPal for ecommerce because they don't have to get their credit card out, just enter their PayPal password.
One thing PayPal does well is have all the features you 100% depend on, already running well. The UX is kind of terrible, but it's at least all there. As a PayPal purchaser, I can enforce a specific shipping address, or a specific source payment method, change it constantly at will, and the seller mostly can't mess it up (PayPal enforces it on my behalf). I can sign up for a subscription, cancel it, all from PayPal's side, and the seller literally can't control that experience or block me from doing that (PayPal enforces that on my behalf too). I can even dispute a transaction with one click (although I've never needed to, so I don't know what happens after that).
I also have a Visa, MasterCard, Amex, Discover, and Simple, and Venmo. Some of these other credit card merchants or cash services have parts of these pieces half implemented. (There are 'fake/disposable' cc numbers and such that try to replicate the 'cancel anytime' thing. You can definitely call a credit card company to block future transactions from a specific company). But to my knowledge, no one else actually has the whole minimum-featureset-for-purchasing figured out and accessible with just clicks online. PayPal does. And they've had it, consistently, for almost a decade.
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So, as a person who writes eCommerce stuff all the time, I get why folks in the industry is sick of it. (It's duplicate steps, we always have to do "real credit cards" merchant, and also a separate "PayPal" integration)
But as a purchaser, I always prefer the PayPal option, rather than handing over a Credit Card to their Stripe/Square/whatever merchant service -- especially for anything with recurring billing. I get why other folks prefer it as well.
I do look around once in a while, for what the alternatives are, but so far PayPal is the only service that lets me run my business from a passive web page. I don't even have my own URL. Every other service seems to have a tutorial showing me what code to install on my server, but frankly hosting and maintaining a server (at home or in the cloud) seems like it would add a dimension of complexity to my business that I don't want to deal with. I certainly don't want to be responsible for handling and storing my customers' credit card numbers and similar data.
I also think that the customer protections are beneficial, since they give people the confidence to buy from a relatively unknown seller.
On top of that, they have a deal with the USPS that lets me generate a first class shipping label, which isn't even available at the USPS website. What I save on postage more than covers the PayPal fee.