Blockchain can be extremely secure. But there is a cost. The cost can be either high or low. But it always has to be considered. Crypto-currencies rely on the routine cracking of cryptographic keys, to grow and remain stable. The cracking costs increase exponentially over time.
If lower security is needed than we use for money systems, we can lower security and implement consensus verifications through groups of un-related (unknown to eachother) verifiers who essentially act as moderators. But these moderators do not moderate content, they only create accuracy based on the consensus by an un-related group of strangers, as to what was said or done. Such consensus eliminates fraud or a need for cryptography. If someone other than you claims to be you, the consensus moderators would use their human intelligence. So (for example) fifty people who do not know eachother, nor do they know who eachother are, would go to work independently on a block of posts. Each moderator might say to themselves something like “that is his usual ip address and MAC address, it comes from his geographic area, the writing style matches his other posts. I vote yes”. Meanwhile some other post comes from outside of the country. Even though the MAC address matches his other posts (a spoof?), the writing style is different and command of the native language is less than typical for this person. So the consensus of votes that this post is from the real account holder is less than fifty percent and the post is labeled as fraudulent. Even in an efficient system, people have to be paid or have to volunteer. You either need exponentially difficult cryptographic keys to crack (which is expensive), or you need human consensus to replace the cryptography.
The fediverse is a better option.
A whole new internet built from the ground-up, could authenticate every communication if you don’t mind a permanent record being kept of everything you say.