It would have been better to suggest that the system support other currencies or at least support the Lightning Network to speed up transactions. It is better than targeting the entire site as if it is responsible for the network congestion that occurs.
Lightning Network is one of methods to go. It is an off-chain solution but one disadvantage is not all users already use Lightning Network and not all users will be ready to go with Lightning Network.
When the site only supports Bitcoin payments, it has very limited options, especially during periods of network congestion. If the site does not support multiple cryptocurrencies, it at least encourages users to at least use the Lightning Network for withdrawals.
What surprises me is that CoinRoyal is an old active platform and that this is not the first time that the Bitcoin network has been in crisis. This means that it was supposed to be preparing its system for such conditions.
Users, in turn, should be equally prepared and can also ask CoinRoyal to support more currencies in different networks.