SCALABILITY ISSUES: some network like Ethrerum and bitcoin can become slow and expensive during high demand.
For ethereum I would understand that it network trx fees are fairly high but not for bitcoin except for when there a network congestion leading to the mempool been overwhelmed, and occurrence that seldom happens. Of which it shouldn't be a valuable reason to risk opting for altcoins.
USABILITY: we the newbies find it so difficult to understand and manage cryptocurrency safely.
We all know that regulations does affects the usability of bitcoin in any society. Government policies has always dictated to a large extend how much people and institutions are willing to use bitcoin as legal tender or means if transaction within a society. So it's not a thing of about being a newbie or oldies.
The first coin every newbie should make their priority should be Bitcoin, though it might have it's own positive side but that's not worth choosing Alts over Bitcoin regardless of any reason Bitcoin stands tall against all and it's the best for hoarding, atleast if someone is going into something that involves finance for the first time, they should start with what's less riskier then they can choose to risk into others in the future when they've benefitted much from the other.
Investing in Bitcoin is not something that someone has to know everything about before doing it, the person mustn't have a degree in certain areas before understanding, merely knowing the basics of what it's all about is enough and you'll gradually understand it better once you've known the basics and practicalise on it, usability is no excuse for newbies nor a criteria for choosing Alts over BTC.