...as folks like Rodney has written, Spanish Cedar has traditionally been used because it mixes degrees of porousness (ability to absorb and maintain humidly without warping on rotting) and natural mold/insect repellant. It's not magic....it can get mold, it can get beetles, it can dry out. But it's a unique wood that way.
I share this for pure entertainment/Sunday night gab purposes only......as someone who has bought/smoked thousands of cigars and had five-figure custom walk-in humidors installed in my prior house....the secret sauce is how many cigars do you want to store. I think Hoosierpipe made this comment earlier.....cigars aren't magic and not honestly as fussy as they are made out to be. There's a lot of ritual/image/lore magic BS out there that's not really harmful...but also way more involved than it needs to be. In my personal opinion space+airflow is the key. Cigars don't care if they are getting humidity from a Boveda pack or a fancy automated fan+humdification gauge system.....distilled water is distilled water. If you have 10-25 cigars.....a plastic-fantastic cigar jar and Boveda pack is fine. You'll be opening the lid and stirring up the airflow. But if you have 300+ cigars you want in a central storage option.....you've got to keep your ariflow moving in a large space to maintain RH and not have pockets of swamp sticks and pockets of tinder. That's where active/fan systems come in.
Again, crazy Sunday talk only.....if you have a humidor/container with the proper flow/humidification-control element Spanish Cedar is not necessary. It doesn't hurt, it's nice....but there are materials today that won't promote mold/off-flavors. Spanish Cedar is nice in that it can naturally soak up or exude some extra humidity, so as long as someone wipes it down/conditions it on first use (acclimate before putting sticks in) it's still a real good material in those 50-100 count humidors for most folks. Where I'd be very careful though is using woods that can seep resins/rot/mold with exposure to 60%+ RH over time....and that's a lot of them.