This isn't the case for most agreements. Most agreements have no 'form' requirements - ie. you could write it on a napkin at a restaurant. As long as both parties believe they are making a legally binding agreement, then they have made a legally binding agreement.
Use of technology doesn't change that. The only time a court would throw out a signature made online is if the online platform was somehow deceiving the parties - for example by showing different text to each side when they click 'i agree'.
The issue isn't necessarily the form of the agreement, it's verifying the identity of the signatories.
If you can't see the other person signing the agreement, you need to verify that the right person is signing it. It's much the same issues that exist with simple passwords versus 2FA; shared accounts, piracy, identity theft, etc.
eIDAS is a set of standards for verifying identity that is backed by law. It allows businesses to follow protocols (some similar to 2FA) with the assurance that it will be held up in court.
Use of technology doesn't change that. The only time a court would throw out a signature made online is if the online platform was somehow deceiving the parties - for example by showing different text to each side when they click 'i agree'.