If I reached out a former colleague for a referral, and they just sent me a link to the careers page, I would be trying to figure out at what point I offended them so deeply. You're not saying that this person is a shoo-in for the role and will be promoted within the year, you're saying that you know what the quality of their work was at the time you worked together.

I can think of people from my first real programming job that I would hire or refer in a heartbeat. I am can also think of a couple who I might just send a link to the careers page.

I mean personally I'd refer them if they didn't suck. Yes, 20 years is a long time but I find that people generally don't change, and successful people are likely to continue being successful.

Going deeper though, obviously networking isn't going to hit every time. That's why you need a whole network and not just one or two people. If the first person you reach out to doesn't want to refer you, it's not a big deal. Just move on to the next one.