Why is there an exemption provided for taxation on Long term Capital Assets tax?

Why is there an exemption provided for taxation on Long term Capital Assets tax?

When a long-term capital asset like a house property or long-term bonds are sold, the gains are usually very large and are taxed at 20%. Thus, the tax liability on this profit also turns out to be a substantial amount as a long-term capital gains tax. However, the I-T Act has given an option of claiming exemption from paying this capital gains tax under sections 54, 54EC &54F, if the taxpayer reinvests the amount in specified investments within a stipulated time.