"Amphibious Operations are hard" is a common trope, but realistically speaking.There are reading material about this from South African wars. Copper wire guided missiles don't do well over the water. Torpedos apparently have a lot of measures to have copper wire guidance work in the water that ATGMs like the TOW lack. Not surprising to be honest considering the difference in cost and the intended use. I haven't found anything unclassified about fiber-optic wire guided missiles. The Spike NLOS was marketed for maritime applications a lot, though. So I guess fiber optic cables have it better in this matter.
If I stay specific to the topic, I think the Taiwanese bet on ATGMs is more of a media hype rather than reality. It just doesn't make sense. These weapons are very short ranged and they aren't going to do anything to landing craft. LSMs and LSTs could tank a lot of hits. Even LCACs should be able to. Furthermore PLA will for certain use a lot of dispersion* to force Taiwan to disperse even more. Smokelaying and communications jamming will be heavily used. If we are talking about the 2030s, APS will be common on AFVs too. These are major problems for ATGM units even without the accounting of the PLA airpower and UCAV fleet.
*: 4-14 beaches stuff is another meme too. Most of Taiwan's West Coast is of shallow gravel reaches. Which means a substaintial portion of the coastline is good enough for an amphibious assault. Especially for tracked vehicles and air cushioned landing craft which are both common in PLA inventory.
Can defenders survive a thorough preparation campaign on a beach? Especially when they don't know which beach will be attacked? There is no Atlantic Wall on Taiwan's West Coast. The most they could do on short notice would probably be tank traps, trenches, and a few rudimentary bunkers.
So is it even reasonable to expect beaches to survive artillery and missiles from PLA's ships, aircraft, and drones?
I genuinely think an amphibious operation would heavily favor PLA. It is PLA who would choose which location/s to land on. When they will do it and they can concentrate far more firepower far quicker than Taiwan.