I have been using Bitcoin for over 10 years and have never used the testnet. Testnet is a tool for developers. Therefore, I recommend all beginners to use the main network right away. You can buy Bitcoin for 20-30 dollars and try transactions on several wallets. The fastest and most convenient wallet in my opinion is Electrum.
It is more relevant to developers for the purpose of building DApps, but it is also relevant to beginners. The goal is to avoid any human error that beginners might make. What's going on in a beginner's head isn't the same as you who's been in
BTC for over 10 years. If those beginners make mistakes when transferring or doing other things with their mainnet
BTC, who will be held responsible?
The best way to learn is by practicing, therefore, for anyone who wants to try
BTC, it is a good idea to practice & understand through the testnet first.
Nothing wrong in using testnet by bigenners although it's created for developpers who want to create Dapps through testnet first before migrating to mainnet, but it become nonsense if you can use the mainnet directly for testing/learning purposes. Address format and other network stuff are somehow different between the two networks, so it's better to buy 10$ or about to try how transactions works with the help of many online tools luke blockchain explorers and mining indicators. I agree with what zasad said without to contradict with your purposes from this topic.