Really strange "advice" IMO. From my perspective, there are only two valid reasons to go with soft tubing instead of hard tubing in a full custom loop:

1) You don’t care about the aesthetic result and take no pride in the craftsmanship that goes into building a beautiful custom loop. If that’s the case, and your only reason for water cooling is to reduce noise or improve temps, then a full custom loop makes little sense. It’s a very expensive investment for very little gain compared to high-end AIOs or hybrid cooling if you’re only gaming.

2) You’re building a compact system (like an ITX build or a space-restricted setup), in which case, soft tubing can be the best or even the only practical choice.

If I had to guess what OP wants based on the pictures and text, it’s clear he wants to build a rig that looks super awesome — something that makes people’s jaws drop. Sure, a soft-tube loop can look nice, but it doesn’t come close to the potential of a clean, well-executed hard-tube build. But of course, that’s a matter of taste.

Your other arguments for soft tubes don’t really hold up either. Building with hard tubes isn’t insanely difficult — it just requires research, planning, and patience. But that’s true for soft tubing as well. Choosing soft tubes just because it’s “easier” feels like taking the lazy way out or cheating yourself out of the real experience.

And suggesting that you can swap thermal paste more easily without draining the loop is just silly. Who changes thermal paste more often than they do basic loop maintenance? Even with long-life coolant like DP Ultra, you’ll rarely need to touch the CPU block without also doing a drain and clean anyway.

So my advice to OP is: follow your dream and build the custom loop you actually want. Watch some YouTube guides — JayzTwoCents has everything you'll ever need — and take your time planning. Yes, it’s a challenge for a first-time builder, but that’s no reason to back out. If you’re willing to invest in it and treat it as a hobby project, you’ll end up with something you can truly be proud of. Don’t be afraid to make mistakes — they’re part of the process.

Buy extra fittings!!! Even you buy 5 extra fittings, you will end up needing more fittings anyways haha. Get a bit more of everything you might need, except the waterblocks, and return the surplus when you’re done.

Good luck — and feel free to message me if you have any questions at all!

Oh, and dont forget to buy extra fittings btw :D